Spiral steel pipe plant in the production process will encounter this question, because the composition of different types of steel, their transition temperature, transition time and the characteristics of the study the same. Even if the same steel, only the end is not the same use, the needs of the arrangements and functions are not the same.
The secondary cooling means cooling from the temperature at the beginning of the phase transformation to the temperature at which the phase transition is completed. The purpose of the secondary cooling is to control the phase change
process by controlling the cooling rate during the phase change and stopping the temperature control to ensure the required metallographic arrangement after the steel is rapidly cooled.
Secondary cooling (air cooling) refers to the phase change to room temperature range of cooling. On the shop in the air-cooled process will occur in the separation of carbonitride, the resulting bainite tempering occurred. On the high-carbon steel or high carbon steel alloy steel phase transformation after the air-cooled, will make the fast cooling, the separation of the super-saturated carbide dispersion continued separation. Such as the phase change is still selected after the completion of technology, you can hinder the carbide separation, adhere to the carbide solid solution, solid solution to strengthen the intention.
2016年12月29日星期四
How to Choose the Spiral Steel Pipe
Spiral steel pipe usage is relatively high, the application is very wide, it should be how to choose before in the selection to pay attention to quality.
The first method is a more professional detection method, that is, by the strength of the pressure vessel to be detected. Commonly, we use atmospheric pressure and water pressure to detect, in this way can detect the working conditions of the spiral steel pipe in the pressure working environment, but also to detect the tightness of the spiral steel pipe, generally take the atmospheric pressure detection, because such security Relatively high, and if the water vapor pressure through the test, then the need to remove the spiral pipe after the water, too much trouble.
The second method is also relatively simple, that is, through the surface of observation. With the naked eye found in the spiral steel pipe in the welding and size of the problem, if necessary, you can also use the standard sample and the products to be compared to find the problem. In general, formal steel pipe company in the production is relatively perfect, on the other hand to beat the metal pipe, if the sound is very crisp and the echo is not very dirty, then the
name is the latest selection of steel pipe, rather than scrap steel recycling
These two methods are commonly used, we can choose a way to test, more secure way is the best to the regular manufacturers, can reduce the use of the process of abuse.
The first method is a more professional detection method, that is, by the strength of the pressure vessel to be detected. Commonly, we use atmospheric pressure and water pressure to detect, in this way can detect the working conditions of the spiral steel pipe in the pressure working environment, but also to detect the tightness of the spiral steel pipe, generally take the atmospheric pressure detection, because such security Relatively high, and if the water vapor pressure through the test, then the need to remove the spiral pipe after the water, too much trouble.
The second method is also relatively simple, that is, through the surface of observation. With the naked eye found in the spiral steel pipe in the welding and size of the problem, if necessary, you can also use the standard sample and the products to be compared to find the problem. In general, formal steel pipe company in the production is relatively perfect, on the other hand to beat the metal pipe, if the sound is very crisp and the echo is not very dirty, then the
name is the latest selection of steel pipe, rather than scrap steel recycling
These two methods are commonly used, we can choose a way to test, more secure way is the best to the regular manufacturers, can reduce the use of the process of abuse.
The Advantages and Disadvantages of Spiral Steel Pipe
The spiral steel pipe is formed by spiral bending of strip steel or coiled plate and is welded with double-side submerged arc welding. The steel pipe is widely used in water, electricity and chemical industry for the following reasons.
1) As long as the change in forming angle, you can use the same width of the strip production of various diameter steel pipe, easy to transfer type.
2) Because it is continuous bending, so the length of spiral pipe length is not restricted, the length can be arbitrarily set.
3) Weld spiral evenly distributed throughout the circumference of the spiral tube, so the size of the spiral tube high precision, strength is also strong.
4) Easy to change the size, suitable for small quantities, more varieties of the production spiral.
Spiral steel pipe with the same specifications than the straight seam welded pipe length, the same specifications wall thickness, the spiral steel pipe to withstand the maximum pressure. The defects of the spiral steel pipe weld are
"oblique defects". In the course of use, the principal stress direction of the steel pipe, that is, the equivalent defect length in the axial direction of the steel pipe is smaller than that of the straight pipe. Secondly, since the
pipeline steel is rolled steel plate, the impact toughness has larger anisotropy, The CVN of the direction can be three times higher than the CVN value perpendicular to the rolling direction.
1) As long as the change in forming angle, you can use the same width of the strip production of various diameter steel pipe, easy to transfer type.
2) Because it is continuous bending, so the length of spiral pipe length is not restricted, the length can be arbitrarily set.
3) Weld spiral evenly distributed throughout the circumference of the spiral tube, so the size of the spiral tube high precision, strength is also strong.
4) Easy to change the size, suitable for small quantities, more varieties of the production spiral.
Spiral steel pipe with the same specifications than the straight seam welded pipe length, the same specifications wall thickness, the spiral steel pipe to withstand the maximum pressure. The defects of the spiral steel pipe weld are
"oblique defects". In the course of use, the principal stress direction of the steel pipe, that is, the equivalent defect length in the axial direction of the steel pipe is smaller than that of the straight pipe. Secondly, since the
pipeline steel is rolled steel plate, the impact toughness has larger anisotropy, The CVN of the direction can be three times higher than the CVN value perpendicular to the rolling direction.
2016年12月27日星期二
Type of Spiral Pipe Fracture
Spiral pipe for liquid delivery with: water supply, drainage. For gas transportation with: gas, steam, liquefied petroleum gas. Petrochemical industry, chemical industry, electric power industry, agricultural irrigation, urban construction, is the development of China's 20 key products (such as water supply, water supply, water supply and drainage).
There are several types of fracture of the spiral tube, according to the situation after the destruction of materials corrosion steel pipe and metal material fracture is roughly the same type is divided into three types, namely: ① cleavage fracture, ② hole reverse fracture, ③ slip surface Separation fracture.
Cleavage fracture of the cross-section of a crystal in strict accordance with the separation, the crystal surface known as the cleavage plane. The fracture strength along this plane is the lowest, and is determined by equation (1-4). The factors that determine the cleavage plane are the specific surface energy y, the interplanar distance of the crystal plane, and the elastic modulus along the normal direction. Cleavage fracture is almost not accompanied by plastic deformation, is a brittle fracture, in the body-centered cubic, closely packed hexagonal gold center. Face-centered cubic metals generally do not undergo cleavage fracture. The shear fracture is the main fracture mechanism of the ductile material. Such as anti-corrosion steel alloy in the second phase of the particles from the role of blocking the slip, increasing resistance to plastic deformation; when the plastic deformation increases, the second phase particles and substrate interface occurs stripping Ang, a small hole; Forming, growing up and merging will form a shear section. For high-purity metal, the absence of second-phase particles, bimetallic wear-resistant composite pipe and therefore will not produce: tiny holes, the result of moving along only the surface area is increasing, and finally form a sliding surface separation section. Anti-corrosion steel pipe spinning compound technology is precisely under the special control of special equipment, the pressure roller rotation and lined tube friction to produce heat, quickly reach the softening point of stainless steel, squeezing the outer extrusion tube to the elastic deformation, the two produce interference Cooperation, to achieve close integration. From the perspective of the organization of the gold, the fracture is divided into transgranular fracture and fracture along the goods.
There are several types of fracture of the spiral tube, according to the situation after the destruction of materials corrosion steel pipe and metal material fracture is roughly the same type is divided into three types, namely: ① cleavage fracture, ② hole reverse fracture, ③ slip surface Separation fracture.
Cleavage fracture of the cross-section of a crystal in strict accordance with the separation, the crystal surface known as the cleavage plane. The fracture strength along this plane is the lowest, and is determined by equation (1-4). The factors that determine the cleavage plane are the specific surface energy y, the interplanar distance of the crystal plane, and the elastic modulus along the normal direction. Cleavage fracture is almost not accompanied by plastic deformation, is a brittle fracture, in the body-centered cubic, closely packed hexagonal gold center. Face-centered cubic metals generally do not undergo cleavage fracture. The shear fracture is the main fracture mechanism of the ductile material. Such as anti-corrosion steel alloy in the second phase of the particles from the role of blocking the slip, increasing resistance to plastic deformation; when the plastic deformation increases, the second phase particles and substrate interface occurs stripping Ang, a small hole; Forming, growing up and merging will form a shear section. For high-purity metal, the absence of second-phase particles, bimetallic wear-resistant composite pipe and therefore will not produce: tiny holes, the result of moving along only the surface area is increasing, and finally form a sliding surface separation section. Anti-corrosion steel pipe spinning compound technology is precisely under the special control of special equipment, the pressure roller rotation and lined tube friction to produce heat, quickly reach the softening point of stainless steel, squeezing the outer extrusion tube to the elastic deformation, the two produce interference Cooperation, to achieve close integration. From the perspective of the organization of the gold, the fracture is divided into transgranular fracture and fracture along the goods.
Quality Inspection of Spiral Steel Pipe
1. From the spiral steel pipe looks. In appearance is to pay attention to those welded joints, seen the appearance is not a drawback, there is a lack of scale, which can be seen through the naked eye, of course, detailed and bilateral theory, Borrow a standard model, gauge and magnifying glass to view. Because of the appearance of welding defects, which means the spiral pipe inside most likely also flawed, even the appearance of effort are not done, inside the effort is difficult to ensure.
2. View approach is to use equipment to view, that is, without the risk of pipe to borrow the case of ultrasonic flaw detection, ray detection, penetration testing, and magnetic flaw detection method can see the spiral pipe has not see the defects. In addition to the defective view, the intensity of the pressurized container is also viewed. Usually there are two kinds of water pressure test and air pressure test. Such a view is to see the spiral steel pipe weld fineness, usually more accurate to use air pressure view. But the pressure is dangerous to view, if not careful to operate in accordance with the rules will appear security incidents.
Spiral steel pipe also have to see through the cracks, there is no porosity, there is no mixing slag, is not there is no penetration of the place, is not there loose arrangements, usually with oil test, with water test or Water test and other measures. In addition to do still water test, the operation can ensure that the pipe without leakage specification.
2. View approach is to use equipment to view, that is, without the risk of pipe to borrow the case of ultrasonic flaw detection, ray detection, penetration testing, and magnetic flaw detection method can see the spiral pipe has not see the defects. In addition to the defective view, the intensity of the pressurized container is also viewed. Usually there are two kinds of water pressure test and air pressure test. Such a view is to see the spiral steel pipe weld fineness, usually more accurate to use air pressure view. But the pressure is dangerous to view, if not careful to operate in accordance with the rules will appear security incidents.
Spiral steel pipe also have to see through the cracks, there is no porosity, there is no mixing slag, is not there is no penetration of the place, is not there loose arrangements, usually with oil test, with water test or Water test and other measures. In addition to do still water test, the operation can ensure that the pipe without leakage specification.
Manufacturing Loss Rate of Spiral Steel Pipe
Spiral steel pipe manufacturing loss rate refers to the spiral pipe in the manufacturing process, the proportion of raw materials, waste, according to professional and technical personnel for many years statistical analysis spiral tube manufacturing loss rate of between 2% -3%.
During the manufacture of spiral steel pipe, the main components of waste are: the first piece of spiral pipe forming the first piece, the tail to tail, the raw material milling, spiral pipe production process necessary steps, if the production can not be normal spiral pipe milling edge, truncated , To the end, the production of steel pipe pass rate is very low.
When spiral steel pipe manufacturing, there are some losses can be avoided, such as spiral pipe weld quality unqualified, can not be repaired, then the spiral pipe quality unqualified, can not be used, resulting in a waste of material. In the manufacturing process, we must strictly control each process, handle the details, so as to improve the spiral tube yield and pass rate, to avoid unnecessary losses, so that can avoid unnecessary cost.
During the manufacture of spiral steel pipe, the main components of waste are: the first piece of spiral pipe forming the first piece, the tail to tail, the raw material milling, spiral pipe production process necessary steps, if the production can not be normal spiral pipe milling edge, truncated , To the end, the production of steel pipe pass rate is very low.
When spiral steel pipe manufacturing, there are some losses can be avoided, such as spiral pipe weld quality unqualified, can not be repaired, then the spiral pipe quality unqualified, can not be used, resulting in a waste of material. In the manufacturing process, we must strictly control each process, handle the details, so as to improve the spiral tube yield and pass rate, to avoid unnecessary losses, so that can avoid unnecessary cost.
2016年12月21日星期三
Influence of Deoxidizer on Straight Seam Steel Pipe
For the straight seam steel pipe, the use of two kinds of deoxidizer has little effect on the total oxygen content in steel after VD treatment, and the total oxygen content in each process after Si-Al-Ba deoxidation, Si-Ca deoxidation effect.
When using Si-Ca and Si-Al-Ba two kinds of deoxidizer, the number and size of inclusions in the smelting process are different, and the number of inclusions in each process after Si-Al-Ba deoxidation is less than Si-Ca deoxidation, and the smaller size.
When Si-Ca and Si-Al-Ba two kinds of deoxidizing agents are used in straight seam welded pipe, the secondary oxidation of liquid steel occurs during the casting process, but the secondary oxidation of Si-Al-Ba deoxidized steel is more serious.
The inclusions in forging materials are different from those in aluminum inclusions. When the Si-Al-Ba deoxidization is used, the inclusions in the forging materials are mainly block and chain-like alumina, while the Si-Ca deoxidation The content of aluminum inclusions in the deoxidized forging material of Si-Ca alloy is less than that of Si-Al-Ba alloy.
When using Si-Ca and Si-Al-Ba two kinds of deoxidizer, the number and size of inclusions in the smelting process are different, and the number of inclusions in each process after Si-Al-Ba deoxidation is less than Si-Ca deoxidation, and the smaller size.
When Si-Ca and Si-Al-Ba two kinds of deoxidizing agents are used in straight seam welded pipe, the secondary oxidation of liquid steel occurs during the casting process, but the secondary oxidation of Si-Al-Ba deoxidized steel is more serious.
The inclusions in forging materials are different from those in aluminum inclusions. When the Si-Al-Ba deoxidization is used, the inclusions in the forging materials are mainly block and chain-like alumina, while the Si-Ca deoxidation The content of aluminum inclusions in the deoxidized forging material of Si-Ca alloy is less than that of Si-Al-Ba alloy.
Characteristics of Welded Steel Tube Slag
Welded steel pipe slag is residual slag inside the weld. From the theoretical analysis, submerged arc welding seam slag generated mainly due to the following three reasons: ① raw materials (including base metal, wire, flux) in the inclusion of more; ② multi-layer welding clean up when the inter-layer; ③ improper selection of welding process parameters is not conducive to the emergence of slag.
According to the production characteristics of straight seam submerged arc welded steel pipe, it can be ruled out that the interlayer cleaning is not clean when the multi-layer welding is done and the slag is generated.
For the inclusions in raw materials and make the weld slag, straight seam steel pipe company to take the pre-test test base metal, replacement of new welding wire and flux and other measures, weld fusion line slag generated only a slight reduction in the proportion, Indicating that inclusions in the raw materials are not the main causes of slag formation.
Therefore, thick-walled LSAW steel pipe welding line slag generated mainly due to improper selection of welding process parameters. The welding parameters of thick-walled submerged arc welded pipe are: line energy, welding current, welding voltage, welding speed, wire spacing, groove size.
According to the production characteristics of straight seam submerged arc welded steel pipe, it can be ruled out that the interlayer cleaning is not clean when the multi-layer welding is done and the slag is generated.
For the inclusions in raw materials and make the weld slag, straight seam steel pipe company to take the pre-test test base metal, replacement of new welding wire and flux and other measures, weld fusion line slag generated only a slight reduction in the proportion, Indicating that inclusions in the raw materials are not the main causes of slag formation.
Therefore, thick-walled LSAW steel pipe welding line slag generated mainly due to improper selection of welding process parameters. The welding parameters of thick-walled submerged arc welded pipe are: line energy, welding current, welding voltage, welding speed, wire spacing, groove size.
2016年12月19日星期一
Weld Treatment of LSAW Steel Pipe
LSAW steel pipe is the strip into the pipe unit, the multi-roll rolling, strip gradually rolled up to form a circular gap open billet, adjust the squeeze roll reduction, so that weld gap control In the 1 ~ 3mm, and make both ends of the welding flush. If the gap is too large, it will reduce the proximity effect, eddy current heat shortage, weld intergranular bonding caused by poor fusion or cracking. Such as between
If the gap is too small, the proximity effect will be increased, the welding heat will be too large, and the weld will be burned; or the weld will be crushed and crushed to form the pit, which will affect the weld surface quality.
Welding process example:
Weld φ32 × 2mm longitudinal welded pipe, for example, briefly describes the process parameters:
Strip specifications: 2 × 98mm bandwidth by medium diameter expansion plus a small amount of molding margin.
Steel material: Q235A
Input excitation voltage: 150V Excitation current: 1.5A Frequency: 50Hz.
Output DC voltage: 11.5kV DC current: 4A Frequency: 120000Hz.
Welding speed: 50 m / min.
Parameter adjustment: according to the welding line energy changes in time to adjust the output voltage and welding speed. Fixed parameters generally do not have to adjust.
If the gap is too small, the proximity effect will be increased, the welding heat will be too large, and the weld will be burned; or the weld will be crushed and crushed to form the pit, which will affect the weld surface quality.
Welding process example:
Weld φ32 × 2mm longitudinal welded pipe, for example, briefly describes the process parameters:
Strip specifications: 2 × 98mm bandwidth by medium diameter expansion plus a small amount of molding margin.
Steel material: Q235A
Input excitation voltage: 150V Excitation current: 1.5A Frequency: 50Hz.
Output DC voltage: 11.5kV DC current: 4A Frequency: 120000Hz.
Welding speed: 50 m / min.
Parameter adjustment: according to the welding line energy changes in time to adjust the output voltage and welding speed. Fixed parameters generally do not have to adjust.
2016年12月15日星期四
Quality Requirements and Welding Temperature Requirements for Large Diameter Straight Seam Steel Tubes
Large diameter straight seam steel pipe welding, including pre-welding, welding and welding outside the three processes. The so-called pre-welding is in the steel forming, the use of continuous high-speed gas shielded welding method of forming steel pipe welding. After the pre-welding, respectively, within the steel pipe, multi-wire submerged arc welding. In the case of high-speed gas-shielded pre-welding, there are currently two methods. One is the use of single-wire dual-power high-current high-speed gas protection pre-welding, such as the United States, Germany that is used in this way; the other is double-wire high-speed gas protection pre-welding, Japan is the use of this method. At present, more applications are monofilament high-speed gas protection pre-welding method, in a reasonable welding process conditions, can achieve not less than 7m / min high speed, and straight bead forming beautiful. Large diameter straight seam steel pipe is a product of the construction industry, steel structure is also one of the building industry, so the steel structure and straight seam steel pipe produced between the inseparable association. Now in the straight seam steel pipe plant in the steel structure accounted for most of the production, so straight seam steel pipe manufacturers for the production of steel pipe with the process and process requirements are very strict, good steel pipe to grasp the straight seam steel pipe Market dynamics, and now a large profit margins of straight seam steel pipe is gone forever, so only a large amount is king, in the increasingly serious competition in how to receive more orders bigger only grasp the quality of products at the same time And constantly grasp the market dynamics and laws to grasp the lifeline of the market.
Large diameter straight seam welded steel pipe as the first process of pre-welding, that is to ensure quality. Pre-welding quality, not only its own quality problems, but also affect the follow-up, the quality of welding. Its quality requirements, targeted mainly as follows:
1, The weld should be continuous, and the appearance of forming to avoid uneven, in order to facilitate the final quality assurance of welding;
2, To ensure the appropriate penetration depth and the amount of welding, it is necessary to ensure that welding does not crack after welding, but also within the welding does not produce burning through the phenomenon;
3, To have a higher welding speed, in order to improve production efficiency.
Large diameter straight seam welded steel pipe as the first process of pre-welding, that is to ensure quality. Pre-welding quality, not only its own quality problems, but also affect the follow-up, the quality of welding. Its quality requirements, targeted mainly as follows:
1, The weld should be continuous, and the appearance of forming to avoid uneven, in order to facilitate the final quality assurance of welding;
2, To ensure the appropriate penetration depth and the amount of welding, it is necessary to ensure that welding does not crack after welding, but also within the welding does not produce burning through the phenomenon;
3, To have a higher welding speed, in order to improve production efficiency.
Factors of Affecting Large Diameter Double-sided Submerged Arc Welding Steel Pipe Mechanical Expanding
There are many factors that affect the quality of large diameter double-sided submerged arc welding steel pipe(dsaw steel pipe). The key factors that directly relate to the quality of diameter forming are the expansion ratio, the amount of axial overlap, the number of segments and the rounded corners, The friction and lubrication between the block and the inner wall of the steel pipe, the shape error of the steel pipe, the expanding speed and the straightening setting of the expanding machine.
(1) When the enlarging rate is small, the roundness error of the steel pipe decreases with the enlarging rate, but when the enlarging rate increases to a certain value, with the enlargement rate increasing, The roundness error of the steel pipe will increase greatly. In the actual production, the expansion ratio is controlled between 0.8% and 1.5%.
(2) The amount of axial overlap has a certain influence on the uniformity of the longitudinal deformation and the diameter-enlarging efficiency of the full-length expansion of the steel tube. The zero overlap amount and the small positive overlap amount are beneficial to alleviate the "bamboo" Improve the diameter expansion efficiency.
(3) Increasing the number of segments, increasing the speed of expansion, increasing friction and lubrication between the segments and the inner wall of the steel pipe, and reducing the friction coefficient of the contact zone are all conducive to the uniform distribution of the wall stress.
(4) The diameter of the pipe to improve the roundness effect is obvious. After the expansion, the roundness error of steel pipe becomes very small.
(1) When the enlarging rate is small, the roundness error of the steel pipe decreases with the enlarging rate, but when the enlarging rate increases to a certain value, with the enlargement rate increasing, The roundness error of the steel pipe will increase greatly. In the actual production, the expansion ratio is controlled between 0.8% and 1.5%.
(2) The amount of axial overlap has a certain influence on the uniformity of the longitudinal deformation and the diameter-enlarging efficiency of the full-length expansion of the steel tube. The zero overlap amount and the small positive overlap amount are beneficial to alleviate the "bamboo" Improve the diameter expansion efficiency.
(3) Increasing the number of segments, increasing the speed of expansion, increasing friction and lubrication between the segments and the inner wall of the steel pipe, and reducing the friction coefficient of the contact zone are all conducive to the uniform distribution of the wall stress.
(4) The diameter of the pipe to improve the roundness effect is obvious. After the expansion, the roundness error of steel pipe becomes very small.
2016年12月13日星期二
Cause Analysis and Attention on Method of Bending Quality
Bending process can be divided into many kinds, there are bending, bending and other means to push, these methods can be divided into two kinds of cold bending and bending bending state. For different bends of the processing technology used is different, different characteristics of the elbow is not the same.
The main reason that causing the quality of elbow decline and the attention method:
1, Pure bending, the tube under the action of the external force M in the outer layer of the lateral arm wall tensile stress and thinning, the inner stress, the role of thickening, resultant N1 and N2 to the tube cross-section changes. Therefore, GBJ235-82, for a variety of pressure levels under the conditions of the RX value and the amount of thinning outside are clearly defined, the purpose is to control the RX and SX To ensure quality.
2, The previous article has been mentioned, the elbow when the lateral tension of the material, the medial position of the neutral axis of pressure and bending method is different from the top bend (compression bending) work in the neutral axis from the outer wall of about 1/3, in the bending (bending) work, the neutral axis from the outer wall 2/3. Therefore, the thin-walled pipe is bent, and it is advantageous to use a bending method.
3, The accuracy of curved tire is also one of the factors affecting the quality of elbow. We bend fetal production, in addition to size requirements to control in a certain tolerance range, but also requires users to use in accordance with bending pipe diameter to select the corresponding bending tire.
4, The pipe itself, the bending performance and surface corrosion, may also affect the quality of elbow. On-site construction, the operator should also be aware of the material being processed pipe, processing performance and surface corrosion to make production judgments.
The main reason that causing the quality of elbow decline and the attention method:
1, Pure bending, the tube under the action of the external force M in the outer layer of the lateral arm wall tensile stress and thinning, the inner stress, the role of thickening, resultant N1 and N2 to the tube cross-section changes. Therefore, GBJ235-82, for a variety of pressure levels under the conditions of the RX value and the amount of thinning outside are clearly defined, the purpose is to control the RX and SX To ensure quality.
2, The previous article has been mentioned, the elbow when the lateral tension of the material, the medial position of the neutral axis of pressure and bending method is different from the top bend (compression bending) work in the neutral axis from the outer wall of about 1/3, in the bending (bending) work, the neutral axis from the outer wall 2/3. Therefore, the thin-walled pipe is bent, and it is advantageous to use a bending method.
3, The accuracy of curved tire is also one of the factors affecting the quality of elbow. We bend fetal production, in addition to size requirements to control in a certain tolerance range, but also requires users to use in accordance with bending pipe diameter to select the corresponding bending tire.
4, The pipe itself, the bending performance and surface corrosion, may also affect the quality of elbow. On-site construction, the operator should also be aware of the material being processed pipe, processing performance and surface corrosion to make production judgments.
Effect of Mechanical Expanding of Double Submerged Arc Welding Longitudinal Seam Steel Pipe
At present, the long-distance transportation of oil and natural gas mainly adopts pipeline. Long-distance pipeline pipeline used in the main spiral pipe submerged arc welded pipe(ssaw steel pipe) and double submerged arc welded straight steel pipe(dsaw steel pipe). As the spiral submerged arc welded pipe is based on strip as raw material, wall thickness is limited, in addition to the existence of spiral submerged arc welded pipe longer, greater residual stress, weld reliability is poor and difficult to overcome the shortcomings of dense population area and reliability requirements of the region, large diameter straight seam submerged arc welded pipe has been gradually replaced by spiral submerged arc welded pipe.
Expanded diameter is a large diameter straight seam submerged arc welded pipe production to ensure the quality of an important process, the standard pipe line pipe submerged arc welded pipe must be expanded process.
1, Effectively improve the dimensional accuracy of steel pipe
At present, there are mainly UO, RB, JCO, C and Hu-Metal for the forming of LSAW steel pipes. The steel pipes produced by these five kinds of molding methods have different geometrical accuracy. As the straight seam submerged arc welding in the tube side of the inside and outside welding, and thus under the action of thermal stress in the steel pipe to be bending deformation, and the longitudinal part of the weld shrinkage larger, so that the straightness of steel pipe is seriously affected; In addition, these five kinds of forming the production of steel pipe, the oval are large, especially JCO and C forming steel pipe. Therefore, we must increase the diameter, the whole circle and other processes to improve the geometric accuracy of steel pipe.
2, Reduce or eliminate in the pipe, the test process caused by the Bauschinger effect
As the steel pipe in the process of forming and testing will produce the Bauschinger effect, so that the yield strength decreased, and the expansion of steel in the cold hardened, expanded diameter can improve the yield strength of steel, thus reducing the strength to achieve steel requirements while increasing the level of waste caused by sheet metal.
3, The elimination of steel pipe forming and welding residual stress
Cold expansion can eliminate the residual stress caused by forming and welding, and improve the distribution of stress in the steel pipe, so as to avoid the occurrence of hydrogen embrittlement and crack in the steel pipe stress concentration area due to the transportation of H2S in oil or natural gas.
In addition, the diameter of the welding quality and welding performance is also a good test.
Expanded diameter is a large diameter straight seam submerged arc welded pipe production to ensure the quality of an important process, the standard pipe line pipe submerged arc welded pipe must be expanded process.
1, Effectively improve the dimensional accuracy of steel pipe
At present, there are mainly UO, RB, JCO, C and Hu-Metal for the forming of LSAW steel pipes. The steel pipes produced by these five kinds of molding methods have different geometrical accuracy. As the straight seam submerged arc welding in the tube side of the inside and outside welding, and thus under the action of thermal stress in the steel pipe to be bending deformation, and the longitudinal part of the weld shrinkage larger, so that the straightness of steel pipe is seriously affected; In addition, these five kinds of forming the production of steel pipe, the oval are large, especially JCO and C forming steel pipe. Therefore, we must increase the diameter, the whole circle and other processes to improve the geometric accuracy of steel pipe.
2, Reduce or eliminate in the pipe, the test process caused by the Bauschinger effect
As the steel pipe in the process of forming and testing will produce the Bauschinger effect, so that the yield strength decreased, and the expansion of steel in the cold hardened, expanded diameter can improve the yield strength of steel, thus reducing the strength to achieve steel requirements while increasing the level of waste caused by sheet metal.
3, The elimination of steel pipe forming and welding residual stress
Cold expansion can eliminate the residual stress caused by forming and welding, and improve the distribution of stress in the steel pipe, so as to avoid the occurrence of hydrogen embrittlement and crack in the steel pipe stress concentration area due to the transportation of H2S in oil or natural gas.
In addition, the diameter of the welding quality and welding performance is also a good test.
Identification Method of Seamless Steel Pipe
Seamless steel pipe identification methods are:
1, With the eyes, welded pipe diameter will have a very obvious weld, the color and other parts of the steel pipe is different.
2, The chemical composition of the material for analysis, the pipe material will be relatively poor, impurity and harmful elements content will be higher.
3, For mechanical performance analysis or process performance analysis, for flaring test, the welded pipe easy to crack.
4, For eddy current testing, eddy current injury control of welded steel pipe may be more alarm.
1, With the eyes, welded pipe diameter will have a very obvious weld, the color and other parts of the steel pipe is different.
2, The chemical composition of the material for analysis, the pipe material will be relatively poor, impurity and harmful elements content will be higher.
3, For mechanical performance analysis or process performance analysis, for flaring test, the welded pipe easy to crack.
4, For eddy current testing, eddy current injury control of welded steel pipe may be more alarm.
Quality Inspection Standard and Operation Process of Cold Drawn Carbon Seamless Steel Pipe
Quality inspection standard and operation process of cold drawn carbon seamless steel pipe are following below:
Production characteristics of the cold drawn tube is from the input to the finished product,which is usually processed through a number of cold deformation and produce hardening, and thus the entire production process by a number of preparatory processes and deformation processes, and has the characteristics of reciprocating cycle, and thus more processes , The production cycle is long, metal consumption, production efficiency is low, the general scale of production are not large.
Cold-rolled, cold-drawn or cold-rolled and cold-drawn combination of cold processing methods is to produce the entire package of equipment combinations, which is the hot-rolled pipe or welded pipe for deep processing unit.
According to the metal processing performance, pipe size, quality requirements and investment and efficiency to choose a different processing methods and the corresponding auxiliary processes. Cold-rolled cold drawn tube of the basic processes are:
(1) The supply of pipe material, the pipe used for hot-rolled or semi-finished product pipe, extrusion pipe and welded pipe;
(2) Pipe preparation, including inspection, bundling, pickling, washing, washing, and in, drying,coating lubricants;
(3) Cold (cold or cold drawing);
(4) Finished product finishing including heat treatment, straightening, sampling, cutting head and tail, inspection (manual inspection and a variety of testing), hydraulic test, oil, packaging, storage and so on. The contents of different products finishing different.
Production characteristics of the cold drawn tube is from the input to the finished product,which is usually processed through a number of cold deformation and produce hardening, and thus the entire production process by a number of preparatory processes and deformation processes, and has the characteristics of reciprocating cycle, and thus more processes , The production cycle is long, metal consumption, production efficiency is low, the general scale of production are not large.
Cold-rolled, cold-drawn or cold-rolled and cold-drawn combination of cold processing methods is to produce the entire package of equipment combinations, which is the hot-rolled pipe or welded pipe for deep processing unit.
According to the metal processing performance, pipe size, quality requirements and investment and efficiency to choose a different processing methods and the corresponding auxiliary processes. Cold-rolled cold drawn tube of the basic processes are:
(1) The supply of pipe material, the pipe used for hot-rolled or semi-finished product pipe, extrusion pipe and welded pipe;
(2) Pipe preparation, including inspection, bundling, pickling, washing, washing, and in, drying,coating lubricants;
(3) Cold (cold or cold drawing);
(4) Finished product finishing including heat treatment, straightening, sampling, cutting head and tail, inspection (manual inspection and a variety of testing), hydraulic test, oil, packaging, storage and so on. The contents of different products finishing different.
2016年12月8日星期四
Manufacturing Process of Carbon Seamless Steel Pipe
According to different production methods of carbon seamless steel pipe can be divided into hot-rolled tube, cold-rolled tube, drawing tube, extrusion tube.
1.Hot-rolled seamless pipe is generally in the automatic production of rolling mill unit. The solid tube blank is inspected and removed from the surface defects, cut into the required length, in the tube end of the perforation end of the centering, and then sent to the heating furnace heating, perforation in the punching machine. In the perforation at the same time continue to rotate and move, in the role of the roll and the head, the tube gradually formed within the cavity, called the capillary. And then sent to the automatic rolling machine to continue rolling. And finally by the whole machine are the whole wall thickness, by sizing machine diameter, to specifications. The use of continuous rolling mill production of hot-rolled seamless steel pipe is a more advanced method.
2.If you want to get smaller and better quality of seamless tubes, must be cold-rolled, cold drawn or a combination of the two methods. Cold rolling is usually carried out on a two-roll mill, in which the steel pipe is rolled in an annular orifice formed by a tapered hole and a non-moving tapered head. Cold drawing is usually carried out on single-chain or double-chain cold drawing machines of 0.5 to 100T.
3.the extrusion method is to heat a good tube on a closed cylinder, squeeze rods and extrusion rod with the movement, so that extrusion from the smaller hole in the extrusion die. This method can produce smaller diameter steel pipe.
1.Hot-rolled seamless pipe is generally in the automatic production of rolling mill unit. The solid tube blank is inspected and removed from the surface defects, cut into the required length, in the tube end of the perforation end of the centering, and then sent to the heating furnace heating, perforation in the punching machine. In the perforation at the same time continue to rotate and move, in the role of the roll and the head, the tube gradually formed within the cavity, called the capillary. And then sent to the automatic rolling machine to continue rolling. And finally by the whole machine are the whole wall thickness, by sizing machine diameter, to specifications. The use of continuous rolling mill production of hot-rolled seamless steel pipe is a more advanced method.
2.If you want to get smaller and better quality of seamless tubes, must be cold-rolled, cold drawn or a combination of the two methods. Cold rolling is usually carried out on a two-roll mill, in which the steel pipe is rolled in an annular orifice formed by a tapered hole and a non-moving tapered head. Cold drawing is usually carried out on single-chain or double-chain cold drawing machines of 0.5 to 100T.
3.the extrusion method is to heat a good tube on a closed cylinder, squeeze rods and extrusion rod with the movement, so that extrusion from the smaller hole in the extrusion die. This method can produce smaller diameter steel pipe.
2016年12月7日星期三
Hardness Test of 40Cr Carbon Seamless Steel Tubes
American Standard carbon seamless steel pipe conduct mechanical performance testing. Mechanical properties of test methods are divided into two categories, one is the tensile test, one is the hardness test.
Tensile tests are made of seamless steel tube samples, the tensile test machine will pull the specimen to the fracture, and then measured one or more mechanical properties, usually only the determination of tensile strength, yield strength, elongation and rate of reduction in area. Tensile test is the most basic metal mechanical properties of test methods, almost all of the metal materials, as long as the mechanical properties are required, are provided for tensile testing. In particular, tensile tests are the only means of testing the mechanical properties of materials that are not easily tested for their hardness.
Hardness test is a hard indenter according to the provisions of the conditions slowly pressed into the sample surface, and then test indentation depth or size, in order to determine the size of the hardness of the material. Hardness test is the mechanical properties of materials testing the most simple, the most rapid and easiest to implement the method. Hardness test is non-destructive, the hardness value of the material and the tensile strength value between the approximate conversion relationship. The hardness of the material can be converted into tensile strength value, which has great practical significance.
As the tensile test is not easy to test, and converted from the hardness to the intensity is very convenient, so more and more people only test the hardness of the material and less test its strength. In particular, due to the hardness of manufacturing technology advances and innovation, some of the original can not directly test the hardness of materials, such as seamless steel tubes, stainless steel and stainless steel, etc., are now possible to directly test the hardness. Therefore, there is a tendency to gradually replace the tensile test with a hardness test.
Tensile tests are made of seamless steel tube samples, the tensile test machine will pull the specimen to the fracture, and then measured one or more mechanical properties, usually only the determination of tensile strength, yield strength, elongation and rate of reduction in area. Tensile test is the most basic metal mechanical properties of test methods, almost all of the metal materials, as long as the mechanical properties are required, are provided for tensile testing. In particular, tensile tests are the only means of testing the mechanical properties of materials that are not easily tested for their hardness.
Hardness test is a hard indenter according to the provisions of the conditions slowly pressed into the sample surface, and then test indentation depth or size, in order to determine the size of the hardness of the material. Hardness test is the mechanical properties of materials testing the most simple, the most rapid and easiest to implement the method. Hardness test is non-destructive, the hardness value of the material and the tensile strength value between the approximate conversion relationship. The hardness of the material can be converted into tensile strength value, which has great practical significance.
As the tensile test is not easy to test, and converted from the hardness to the intensity is very convenient, so more and more people only test the hardness of the material and less test its strength. In particular, due to the hardness of manufacturing technology advances and innovation, some of the original can not directly test the hardness of materials, such as seamless steel tubes, stainless steel and stainless steel, etc., are now possible to directly test the hardness. Therefore, there is a tendency to gradually replace the tensile test with a hardness test.
2016年12月5日星期一
The Practice of Large Diameter Spiral Pipe Demagnetization
The current demagnetization of large diameter spiral steel pipe is usually used in the DC demagnetization coil, the demagnetization coil will be added to the magnetic particle inspection machine in the future, but the demagnetization effect does not enable customers to meet the problem is that the DC demagnetization field occurs only reverse half of the magnetic field, How to demagnetize the internal remanence magnetic steel reverse some offset, the external performance of the residual magnetism to stay in the required range, so the role is very unstable. Often in the field can pass, after the transfer, hit, the magnetic field and overrun. The reason is that the internal magnetic domain is not through the "magnetic exercise" in a very unstable situation.
The demagnetization of large diameter spiral steel tube is the national standard 30GS following, HT30D steel tube demagnetization system can be remanufactured steel tube stability to 10GS remnant, in order to avoid the future in the process of remanence and then rebound. Specifications: Dimensions: 400 * 500 * 600mm, operating voltage: 220V, operating current: 5-20A successive adjustable, operating frequency: 0-50Hz successive adjustable, demagnetization coil diameter scale: 100-250 (or customer demand meter).
The demagnetization of large diameter spiral steel tube is the national standard 30GS following, HT30D steel tube demagnetization system can be remanufactured steel tube stability to 10GS remnant, in order to avoid the future in the process of remanence and then rebound. Specifications: Dimensions: 400 * 500 * 600mm, operating voltage: 220V, operating current: 5-20A successive adjustable, operating frequency: 0-50Hz successive adjustable, demagnetization coil diameter scale: 100-250 (or customer demand meter).
Precautions for Installation of Carbon Seamless Steel Pipe
(1) Carbon seamless steel pipe should be carefully installed before the following carefully checked to ensure the quality of pipe and pipe.
A. Check the factory and pipe fittings factory certificate, quality certificate or test records, test records and other technical information, and should comply with existing national standards.
B. Check the quality marks of the pipe and fittings, expansion joint to meet the technical document and the current national standard. If there is any problem, replace or take the measures.
C. Check the quality of the outer surface of the pipe and pipe fittings, wall thickness should be consistent with national standards. The ellipticity is not allowed to exceed the specified range. No cracks, no shrinkage, no slag, no
folding, no heavy skin, no trachoma, no pinhole, no more than the thickness of the local pit tolerance, no bumps and other quality problems, and the tube Internal and external surface without serious corrosion when the pipe and pipe
fittings qualified.
(2) When the pipe surface rust less number of pipes can not be used when the number of hand-rust, the general hand-rust is a wire brush, wire cloth, emery cloth and other friction, remove the rust on the pipe surface, and then dry cotton
yarn Wipe or clean, so that the pipe surface exposed metallic luster.
(3) When the pipe surface rust more, and the larger number of pipes and generally use mechanical rust or sand blasting rust or pickling rust. Pickling rust rust when the general use of sulfuric acid or hydrochloric acid.
(4) Brush the surface of the pipe type of anti-rust paint should be selected according to design requirements, commonly used red lead rust paint, epoxy paint, etc., the surface finish is generally blending paint.
Before painting, clean the surface of the pipe clean dust, dirt, burr, oil and water. Brush should be uniform coating, do not leak coating, brush the paint after the eligibility criteria for attachment firmly, no flaking, no wrinkles, no
bubbles, no leakage coating, no damage and other defects.
A. Check the factory and pipe fittings factory certificate, quality certificate or test records, test records and other technical information, and should comply with existing national standards.
B. Check the quality marks of the pipe and fittings, expansion joint to meet the technical document and the current national standard. If there is any problem, replace or take the measures.
C. Check the quality of the outer surface of the pipe and pipe fittings, wall thickness should be consistent with national standards. The ellipticity is not allowed to exceed the specified range. No cracks, no shrinkage, no slag, no
folding, no heavy skin, no trachoma, no pinhole, no more than the thickness of the local pit tolerance, no bumps and other quality problems, and the tube Internal and external surface without serious corrosion when the pipe and pipe
fittings qualified.
(2) When the pipe surface rust less number of pipes can not be used when the number of hand-rust, the general hand-rust is a wire brush, wire cloth, emery cloth and other friction, remove the rust on the pipe surface, and then dry cotton
yarn Wipe or clean, so that the pipe surface exposed metallic luster.
(3) When the pipe surface rust more, and the larger number of pipes and generally use mechanical rust or sand blasting rust or pickling rust. Pickling rust rust when the general use of sulfuric acid or hydrochloric acid.
(4) Brush the surface of the pipe type of anti-rust paint should be selected according to design requirements, commonly used red lead rust paint, epoxy paint, etc., the surface finish is generally blending paint.
Before painting, clean the surface of the pipe clean dust, dirt, burr, oil and water. Brush should be uniform coating, do not leak coating, brush the paint after the eligibility criteria for attachment firmly, no flaking, no wrinkles, no
bubbles, no leakage coating, no damage and other defects.
2016年11月30日星期三
Characteristics of Alloy Steel Continuous Casting Process
Alloy steel casting process compared with carbon steel has the following characteristics:
(1) According to the needs of the cast steel, the liquid steel purity, composition and pouring temperature, especially the control of trace element content, are required to achieve the specified value. This special steel continuous casting furnace must be equipped with refining equipment.
(2) Mold should be used high-frequency, small amplitude vibration.
(3) Selection of good performance and the protection of the whole process of pouring casting to ensure the quality of slab.
(4) The best use of large capacity, deep melt pool, and build a retaining wall, the dam of the tank, give full play to the metallurgical function of the middle tank.
(5) It should use the appropriate refractory materials to reduce consumption and improve the purity of steel.
(6) The use of mold level automatic control to reduce surface fluctuations.
(1) According to the needs of the cast steel, the liquid steel purity, composition and pouring temperature, especially the control of trace element content, are required to achieve the specified value. This special steel continuous casting furnace must be equipped with refining equipment.
(2) Mold should be used high-frequency, small amplitude vibration.
(3) Selection of good performance and the protection of the whole process of pouring casting to ensure the quality of slab.
(4) The best use of large capacity, deep melt pool, and build a retaining wall, the dam of the tank, give full play to the metallurgical function of the middle tank.
(5) It should use the appropriate refractory materials to reduce consumption and improve the purity of steel.
(6) The use of mold level automatic control to reduce surface fluctuations.
Surface Quality Analysis of High Precision Cold Drawn Seamless Steel
Surface defect of cold drawn tube inner wall
High precision cold drawn tube surface roughness Ra ≤ 0.8μm, diameter size accuracy can reach H9 ~ H10, only to ensure that after honing to H7 ~ H8 bore size and Ra ≤ 0.2μm of the internal surface roughness requirements. In addition to the honing machine equipment precision, the cold drawn tube surface quality is another key point, cold drawn tube internal surface defects by the domestic A factory measured data classification, there are three kinds of main honing pipe surface roughness.
1. Pitting
After rough drawing, the surface can be found by many pits-like defects, such defects will not seriously affect the smoothness of the cylinder bore, for the cylinder is a waste.
2. Scratch
Scratch defects are cold drawn, generally along the axis of a steel pipe along the direction of the scratches, there must be more than the depth of the scratches honing margin, it is possible to grind away such defects, processing a
qualified cylinder.
3. Not round
Cold drawn seamless steel pipe in the production, fixed on the mandrel of the internal model can be floating up and down, so cold drawn tube diameter is not as straight as the machining tube. In addition, some hot-rolled tube, with the wall thickness difference between the larger, cold drawing deformation due to the existence of deformation within the tube is not uniform, easy to produce cold drawn tube does not dot. The tube after honing will find a hole in the hole with other parts of the reflective surface of different degrees, if the grinding volume is small, where even the cold drawn when the phosphate layer is not removed. Seriously affecting the cylinder surface quality.
The measures are as follows:
(1) Cold drawn seamless steel pipe directly into the cylinder, the quality can not be guaranteed, it is best to stay 0.2mm (wall thickness) honing, grinding and then processing use.
(2) Cold drawn seamless steel pipe inner hole defect is the impact of the cylinder bore hole surface quality of the main reasons.
(3) Pitting defects produced by the hot-rolled tube, cold drawing can reduce the depth of the defect can not eliminate the defect.
(4) To increase the amount of cold drawn deformation, preferably hot-rolled seamless steel tube blank, hot-rolled tube defects in the hole clean-up, can improve the cold drawn seamless steel pipe wall surface quality, reduce honing
margins, reduce honing costs and improve Honing production efficiency.
High precision cold drawn tube surface roughness Ra ≤ 0.8μm, diameter size accuracy can reach H9 ~ H10, only to ensure that after honing to H7 ~ H8 bore size and Ra ≤ 0.2μm of the internal surface roughness requirements. In addition to the honing machine equipment precision, the cold drawn tube surface quality is another key point, cold drawn tube internal surface defects by the domestic A factory measured data classification, there are three kinds of main honing pipe surface roughness.
1. Pitting
After rough drawing, the surface can be found by many pits-like defects, such defects will not seriously affect the smoothness of the cylinder bore, for the cylinder is a waste.
2. Scratch
Scratch defects are cold drawn, generally along the axis of a steel pipe along the direction of the scratches, there must be more than the depth of the scratches honing margin, it is possible to grind away such defects, processing a
qualified cylinder.
3. Not round
Cold drawn seamless steel pipe in the production, fixed on the mandrel of the internal model can be floating up and down, so cold drawn tube diameter is not as straight as the machining tube. In addition, some hot-rolled tube, with the wall thickness difference between the larger, cold drawing deformation due to the existence of deformation within the tube is not uniform, easy to produce cold drawn tube does not dot. The tube after honing will find a hole in the hole with other parts of the reflective surface of different degrees, if the grinding volume is small, where even the cold drawn when the phosphate layer is not removed. Seriously affecting the cylinder surface quality.
The measures are as follows:
(1) Cold drawn seamless steel pipe directly into the cylinder, the quality can not be guaranteed, it is best to stay 0.2mm (wall thickness) honing, grinding and then processing use.
(2) Cold drawn seamless steel pipe inner hole defect is the impact of the cylinder bore hole surface quality of the main reasons.
(3) Pitting defects produced by the hot-rolled tube, cold drawing can reduce the depth of the defect can not eliminate the defect.
(4) To increase the amount of cold drawn deformation, preferably hot-rolled seamless steel tube blank, hot-rolled tube defects in the hole clean-up, can improve the cold drawn seamless steel pipe wall surface quality, reduce honing
margins, reduce honing costs and improve Honing production efficiency.
2016年11月24日星期四
Easy to Crack Situation for Stainless Steel Pipe
At room temperature, deformation-induced martensite was produced in both tensile, bending and rolling conditions, and the content of stainless steel increased with the increase of cold working deformation. A lot of experiments show that the deformed layers, deformed twins and strain-induced martensite appear in different degree during the deformation process of the seamless tube, and dislocation plugged and dislocated cellular structure are formed near the grain boundary and annealing twin.
These deformed microstructures contribute to work hardening. Seamless solution for the main purpose is to eliminate the material to reduce stress and hardness, improve the formability of stainless steel seamless pipe. The hardness after treatment is too high that the softening effect is poor, the residual stress is not fully released, because the residual stress caused by lattice distortion will also change the hardness value. It is due to the presence of residual stress, resulting in stainless steel tube flaring easy to stress concentration where the cracks, thus affecting the flaring performance. As the grain boundaries and grain boundaries on both sides of the grain orientation difference, increasing the resistance of dislocation slip in the crystal, so the main role of grain boundary is to impede dislocation movement. The finer the grains, the more the grain boundaries, the greater the resistance to dislocation slip, the higher the yield strength of the steel, the formation of grain boundary strengthening, resulting in work hardening; so the smaller the grain in the flaring The more prone to work hardening.
These deformed microstructures contribute to work hardening. Seamless solution for the main purpose is to eliminate the material to reduce stress and hardness, improve the formability of stainless steel seamless pipe. The hardness after treatment is too high that the softening effect is poor, the residual stress is not fully released, because the residual stress caused by lattice distortion will also change the hardness value. It is due to the presence of residual stress, resulting in stainless steel tube flaring easy to stress concentration where the cracks, thus affecting the flaring performance. As the grain boundaries and grain boundaries on both sides of the grain orientation difference, increasing the resistance of dislocation slip in the crystal, so the main role of grain boundary is to impede dislocation movement. The finer the grains, the more the grain boundaries, the greater the resistance to dislocation slip, the higher the yield strength of the steel, the formation of grain boundary strengthening, resulting in work hardening; so the smaller the grain in the flaring The more prone to work hardening.
Manufacturing Method of Carbon Seamless Seel Pipe
Carbon seamless steel pipe is generally in the automatic production of rolling pipe unit. The solid blank is inspected and removed from the surface defects, cut into the required length, in the tube end of the perforation end of the centering, and then sent to the heating in furnace, perforation in the punch.continue to rotate and move when perforation, in the role of the roll and the head, the tube gradually formed within the cavity, called the capillary. And then sent to the automatic rolling machine to continue rolling. And finally by the whole machine are the whole wall thickness, by sizing machine diameter, to specifications. The use of continuous rolling mill production of hot-rolled seamless steel pipe is a more advanced method.
If you want to get smaller and better quality of seamless tubes, it must be cold-rolled, cold drawn or a combination of the two methods. Cold rolling is usually carried out on a two-roll mill, in which the steel pipe is rolled in an annular orifice formed by a tapered hole and a non-moving tapered head. Cold drawing is usually carried out on single-chain or double-chain cold drawing machines of 0.5 to 100T.
The extruding method is to place the heated tube in a closed extruding cylinder which is moved with the extruding rod to squeeze the extrudate from the smaller die hole. This method can produce smaller diameter steel pipe.
If you want to get smaller and better quality of seamless tubes, it must be cold-rolled, cold drawn or a combination of the two methods. Cold rolling is usually carried out on a two-roll mill, in which the steel pipe is rolled in an annular orifice formed by a tapered hole and a non-moving tapered head. Cold drawing is usually carried out on single-chain or double-chain cold drawing machines of 0.5 to 100T.
The extruding method is to place the heated tube in a closed extruding cylinder which is moved with the extruding rod to squeeze the extrudate from the smaller die hole. This method can produce smaller diameter steel pipe.
2016年11月23日星期三
Versatility of Seamless Pipes from Wooden House to Manufacturing Units
The wooden houses are the once which are loved by everyone, because they are cool and looks super exciting, but there are several problem comes in constructing and taking care of that kind of home. The problems are water- which can result in rotten walls, sun- which can burn, other than that it has less life than a cemented house. Still it is the most loved construction among other, so here is a base through which you can give long and strength full life to the wooden house.
It is a seamless pipe which can cure the wooden house from the effect of water and keep it away from other sewage problem. SMLS pipes are the widest range, which can be used for the construction and mining purposes. It comes up to 1 to 24'' inch which have the solution of each and every issue of blocking of water in wooden house. For example, a wooden house may need SMLS pipe in order to make the wetness of the water away. These pipes are used in high and low temperature range. It is prepared according to ASTM and API in the complete schedule series. Its strength is up to 1000 ksi.
Manufacturing process
It is prepared through the electric resistance welding, fusion welding, double submerged arc welding and seamless pipe manufacturing. Its manufacturing starts with the transformation of raw material into steel bar. After that it is put in different types of rolling mills, then the bars are use to form the solid round shape called billet, which is heated, pushed and pierced to produce hollow tube or shell. Just because of the heating process, seamless pipes are concluded to have consistent steel pattern.
Uses in other industries
Seamless tubes are the star of high pressure gas and fluid industry, oil and petrochemical industries, power industries. It is a product of steel which is a non-reactive thing, whether it comes in contact of any chemical, it is a safest medium to transfer and dispense the chemicals, water and oil to another tank for further process. It has several uses in manufacturing units as well as in mining rather than that the water supply in various areas is also done with the help of these pipes who are versatile to use in any condition and pursue long life.
I hope the readers will get the versatility of the SMLS pipes, because it can be used in various industries from wooden house to manufacturing units. It has the wide range of pipes for different purposes.
It is a seamless pipe which can cure the wooden house from the effect of water and keep it away from other sewage problem. SMLS pipes are the widest range, which can be used for the construction and mining purposes. It comes up to 1 to 24'' inch which have the solution of each and every issue of blocking of water in wooden house. For example, a wooden house may need SMLS pipe in order to make the wetness of the water away. These pipes are used in high and low temperature range. It is prepared according to ASTM and API in the complete schedule series. Its strength is up to 1000 ksi.
Manufacturing process
It is prepared through the electric resistance welding, fusion welding, double submerged arc welding and seamless pipe manufacturing. Its manufacturing starts with the transformation of raw material into steel bar. After that it is put in different types of rolling mills, then the bars are use to form the solid round shape called billet, which is heated, pushed and pierced to produce hollow tube or shell. Just because of the heating process, seamless pipes are concluded to have consistent steel pattern.
Uses in other industries
Seamless tubes are the star of high pressure gas and fluid industry, oil and petrochemical industries, power industries. It is a product of steel which is a non-reactive thing, whether it comes in contact of any chemical, it is a safest medium to transfer and dispense the chemicals, water and oil to another tank for further process. It has several uses in manufacturing units as well as in mining rather than that the water supply in various areas is also done with the help of these pipes who are versatile to use in any condition and pursue long life.
I hope the readers will get the versatility of the SMLS pipes, because it can be used in various industries from wooden house to manufacturing units. It has the wide range of pipes for different purposes.
Stress Relief Annealing
The precision seamless steel tube to a certain temperature (usually in the phase transition temperature or recrystallization temperature below), the insulation for some time, and then slowly cooling, to eliminate stress in a variety of precision seamless steel tube annealing process.
In press working, casting, welding, heat treatment, cutting and other processes, the product may produce internal stress. In most cases, the metal will retain a portion of its residual stress after the process has ended. Residual stress can lead to fracture, deformation or size change of the workpiece, residual stress also improve the metal chemical activity, in the residual tensile stress is particularly vulnerable to intergranular corrosion caused by rupture. Therefore, the residual stress will affect the performance of precision seamless steel pipe or lead to premature failure of the workpiece.
When the stress is less than the yield strength of the material at the temperature below which the stress is less than the yield strength of the material at the temperature of the stress relaxation temperature, When the residual stress relaxation to achieve the purpose of elimination. In the stress relief annealing, the workpiece is generally slowly heated to a lower temperature (gray cast iron is 500 ~ 550 ℃, precision seamless steel pipe is 500 ~ 650 ℃, non-ferrous metal alloy stamping parts for the recrystallization temperature below), to maintain a period of time , And then slowly cooled to prevent the generation of new residual stresses.
Stress-relief annealing does not completely eliminate the residual stress inside the precision seamless steel tube, but is largely eliminated. For the complete removal of residual stress, precision seamless steel tubes need to be heated to a higher temperature. In this condition, may bring other organizational changes, endangering the use of precision seamless steel pipe performance.
In press working, casting, welding, heat treatment, cutting and other processes, the product may produce internal stress. In most cases, the metal will retain a portion of its residual stress after the process has ended. Residual stress can lead to fracture, deformation or size change of the workpiece, residual stress also improve the metal chemical activity, in the residual tensile stress is particularly vulnerable to intergranular corrosion caused by rupture. Therefore, the residual stress will affect the performance of precision seamless steel pipe or lead to premature failure of the workpiece.
When the stress is less than the yield strength of the material at the temperature below which the stress is less than the yield strength of the material at the temperature of the stress relaxation temperature, When the residual stress relaxation to achieve the purpose of elimination. In the stress relief annealing, the workpiece is generally slowly heated to a lower temperature (gray cast iron is 500 ~ 550 ℃, precision seamless steel pipe is 500 ~ 650 ℃, non-ferrous metal alloy stamping parts for the recrystallization temperature below), to maintain a period of time , And then slowly cooled to prevent the generation of new residual stresses.
Stress-relief annealing does not completely eliminate the residual stress inside the precision seamless steel tube, but is largely eliminated. For the complete removal of residual stress, precision seamless steel tubes need to be heated to a higher temperature. In this condition, may bring other organizational changes, endangering the use of precision seamless steel pipe performance.
2016年11月3日星期四
Method of Straight Seam Steel Pipe in Preheat Deformation
First, the rational selection. On the mold should be selected for precision messy material deformation of a good micro-deformation of steel, carbide segregation serious die steel should be a reasonable casting and quenching and tempering
treatment, the larger and can not be casting mold steel can be solid solution double fine heat treatment. Reasonable choice of heating temperature, control the heating rate, the mold can be used for precision messy slow heating,preheating and other methods of equilibrium heating to reduce the mold heat treatment deformation.
Second, the correct operation of the heat treatment process and a reasonable tempering heat treatment process is to reduce the deformation of a useful tool for precision messy method. Precise messy mold deformation reasons are often
messy, but we only need to master the deformation rules, analysis of the causes of their attack, the choice of abnormal methods to avoid the deformation of the mold can be reduced, but also can be controlled.
Third, the precision messy mold carry out pre-heat treatment to eliminate the mechanical processing of the rest of the stress occurred. On the precision messy mold, in the conditions permitting, try to use vacuum hardening and quenching
after cryogenic treatment. In ensuring the hardness of the mold under the premise, try to use pre-cooling, grading cooling quenching or quenching process.
Fourth, the mold planning description should be reasonable thickness should not be too poor, the shape should be symmetrical, deformation on the larger mold to master the deformation rules, set aside allowance for large, sophisticated messy mold can be used in combination planning. For some precision messy mold can use pre-heat treatment, aging heat treatment, quenched and tempered nitriding heat treatment to control the accuracy of the mold. In the repair mold sand holes, pores, wear and other defects, the choice of cold welding and other heat affected small repair equipment to avoid the repair process deformation of the attack.
treatment, the larger and can not be casting mold steel can be solid solution double fine heat treatment. Reasonable choice of heating temperature, control the heating rate, the mold can be used for precision messy slow heating,preheating and other methods of equilibrium heating to reduce the mold heat treatment deformation.
Second, the correct operation of the heat treatment process and a reasonable tempering heat treatment process is to reduce the deformation of a useful tool for precision messy method. Precise messy mold deformation reasons are often
messy, but we only need to master the deformation rules, analysis of the causes of their attack, the choice of abnormal methods to avoid the deformation of the mold can be reduced, but also can be controlled.
Third, the precision messy mold carry out pre-heat treatment to eliminate the mechanical processing of the rest of the stress occurred. On the precision messy mold, in the conditions permitting, try to use vacuum hardening and quenching
after cryogenic treatment. In ensuring the hardness of the mold under the premise, try to use pre-cooling, grading cooling quenching or quenching process.
Fourth, the mold planning description should be reasonable thickness should not be too poor, the shape should be symmetrical, deformation on the larger mold to master the deformation rules, set aside allowance for large, sophisticated messy mold can be used in combination planning. For some precision messy mold can use pre-heat treatment, aging heat treatment, quenched and tempered nitriding heat treatment to control the accuracy of the mold. In the repair mold sand holes, pores, wear and other defects, the choice of cold welding and other heat affected small repair equipment to avoid the repair process deformation of the attack.
How to Weld for the ERW Steel Pipe in Winter
To ensure that the erw steel pipe in the winter welding perfect follow the following steps:
First, increase the welding current welding, slow down the welding speed, the appropriate increase in the cross-sectional area and length of the weld, if necessary, preheat.
Second, not outside the groove on the base metal to start arc, arc extinction to be filled when the pit.
Third, as far as possible not in low temperature conditions for bending, correction and assembly weldments.
Fourth, preheating before welding, welding process to strictly maintain the interlayer temperature should not be lower than the preheating temperature.
Fifth, the use of low hydrogen or ultra-low hydrogen welding materials.
Six, the entire weld should be finished as far as possible to avoid interruption.
First, increase the welding current welding, slow down the welding speed, the appropriate increase in the cross-sectional area and length of the weld, if necessary, preheat.
Second, not outside the groove on the base metal to start arc, arc extinction to be filled when the pit.
Third, as far as possible not in low temperature conditions for bending, correction and assembly weldments.
Fourth, preheating before welding, welding process to strictly maintain the interlayer temperature should not be lower than the preheating temperature.
Fifth, the use of low hydrogen or ultra-low hydrogen welding materials.
Six, the entire weld should be finished as far as possible to avoid interruption.
Quality Inspection Methods and Equipment of Seamless Steel Pipe
Quality inspection methods and equipment of seamless steel pipe
1, Chemical composition analysis
Instrumental analysis and chemical analysis can be used. For chemical analysis of the sample sub-smelting samples, ingot drill cuttings samples, pipe samples. Smelting samples are generally used instrumental analysis method, the pipe finished sample using chemical analysis and analysis together. Commonly used chemical analysis instruments are: infrared carbon and sulfur analyzer, direct reading spectrometer, X-ray fluorescence spectrometer.
2, Size and shape detection
Check the contents include: wall thickness, diameter, length, bending, ellipticity, port slope and the obtuse angle and cross-sectional shape of special-shaped steel pipe.
3, Surface quality testing
Naked eye inspection and nondestructive inspection. There are many non-destructive testing methods such as: ultrasonic testing, eddy current testing, magnetic detection, magnetic flux leakage testing, electromagnetic and ultrasonic flaw detection flaw detection. Each method has its own advantages and disadvantages: suitable for the detection of steel pipe surface or near the surface: eddy current testing, magnetic detection, magnetic flux leakage detection, penetration testing. Penetration testing is limited to inspection of the surface defects of the steel pipe. Magnetic particle inspection, magnetic flux leakage testing, eddy current testing is limited to ferromagnetic material inspection. Eddy current testing is more sensitive to point defects, other crack detection sensitivity. Ultrasonic detection of steel pipe surface detection reaction is relatively rapid, the internal qualitative analysis of steel there are still some difficulties, and ultrasonic inspection is also affected by the shape and grain size of steel pipe restrictions.
4, Chemical properties testing
(Tensile test, toughness test, hardness test), hydraulic test and corrosion test (intergranular corrosion test, anti-hydrogen cracking test-HIC, anti-sulfide stress cracking test-SSCC) at room temperature or a certain temperature.
5, Steel pipe process performance test
Including flattening experiments, ring pull tests, flaring and crimping experiments, bending experiments.
6, Metallographic analysis
Including low magnification and high magnification.
7, Oil-specific pipe thread parameter detection
Including coupling pattern detection, pipe thread detection and tightening of the pipe body and coupling after the detection.
1, Chemical composition analysis
Instrumental analysis and chemical analysis can be used. For chemical analysis of the sample sub-smelting samples, ingot drill cuttings samples, pipe samples. Smelting samples are generally used instrumental analysis method, the pipe finished sample using chemical analysis and analysis together. Commonly used chemical analysis instruments are: infrared carbon and sulfur analyzer, direct reading spectrometer, X-ray fluorescence spectrometer.
2, Size and shape detection
Check the contents include: wall thickness, diameter, length, bending, ellipticity, port slope and the obtuse angle and cross-sectional shape of special-shaped steel pipe.
3, Surface quality testing
Naked eye inspection and nondestructive inspection. There are many non-destructive testing methods such as: ultrasonic testing, eddy current testing, magnetic detection, magnetic flux leakage testing, electromagnetic and ultrasonic flaw detection flaw detection. Each method has its own advantages and disadvantages: suitable for the detection of steel pipe surface or near the surface: eddy current testing, magnetic detection, magnetic flux leakage detection, penetration testing. Penetration testing is limited to inspection of the surface defects of the steel pipe. Magnetic particle inspection, magnetic flux leakage testing, eddy current testing is limited to ferromagnetic material inspection. Eddy current testing is more sensitive to point defects, other crack detection sensitivity. Ultrasonic detection of steel pipe surface detection reaction is relatively rapid, the internal qualitative analysis of steel there are still some difficulties, and ultrasonic inspection is also affected by the shape and grain size of steel pipe restrictions.
4, Chemical properties testing
(Tensile test, toughness test, hardness test), hydraulic test and corrosion test (intergranular corrosion test, anti-hydrogen cracking test-HIC, anti-sulfide stress cracking test-SSCC) at room temperature or a certain temperature.
5, Steel pipe process performance test
Including flattening experiments, ring pull tests, flaring and crimping experiments, bending experiments.
6, Metallographic analysis
Including low magnification and high magnification.
7, Oil-specific pipe thread parameter detection
Including coupling pattern detection, pipe thread detection and tightening of the pipe body and coupling after the detection.
Quality Requirements for Seamless Steel Pipe
Quality requirements for seamless steel pipe
1, Chemical composition
In order to improve the uniformity of chemical composition in steel and the purity of steel, to reduce the non-metallic inclusions in the tube and to improve the distribution state, it is often used to improve the chemical composition of the steel, such as As Sn Sb Bi Pb and gas NHO. External refining equipment for refining of molten steel, and even the use of electroslag furnace on the tube re-melting refining.
2, Dimensional accuracy and shape
The geometry of the seamless steel pipe mainly includes the outer diameter, wall thickness, ellipticity, length, curvature, pipe end face inclination, groove angle and the blunt edge, cross-sectional size of the steel pipe.
3, Surface quality
The standard specifies the requirements for the "smooth surface" of seamless steel tubes. Common defects include: cracks, hair lines, inside the fold, outside the fold, rolling broken, the straight, outside the straight, separated layer, scar, pits, convex package, Ma Hang (Ma) , The spiral Road, outside the spiral Road, Green Line, correction concave, such as roller. Crack, slight internal and external straight, minor internal and external spiral, straightening, and so
on. In addition to the internal and external cracks, cracks, broken, rolling, Concave, roll as a general defect.
4, Physical and chemical properties
Including mechanical properties at room temperature and mechanical properties at certain temperatures (heat and low temperature properties) and corrosion resistance (such as anti-oxidation, water erosion, acid and alkali resistance and other properties) under normal circumstances depends on the chemical composition of steel, Performance and steel purity and steel heat treatment methods. In some cases, the rolling temperature and the degree of deformation of the steel pipe will also affect the performance of the steel pipe.
5, Process performance
Including flaring, flattening, crimping, bending, pulling and welding performance.
6, Microstructure
Including the low-power steel pipe and high-power organization.
7, Special requirements
In the user's use of steel pipe other than the standard requirements.
1, Chemical composition
In order to improve the uniformity of chemical composition in steel and the purity of steel, to reduce the non-metallic inclusions in the tube and to improve the distribution state, it is often used to improve the chemical composition of the steel, such as As Sn Sb Bi Pb and gas NHO. External refining equipment for refining of molten steel, and even the use of electroslag furnace on the tube re-melting refining.
2, Dimensional accuracy and shape
The geometry of the seamless steel pipe mainly includes the outer diameter, wall thickness, ellipticity, length, curvature, pipe end face inclination, groove angle and the blunt edge, cross-sectional size of the steel pipe.
3, Surface quality
The standard specifies the requirements for the "smooth surface" of seamless steel tubes. Common defects include: cracks, hair lines, inside the fold, outside the fold, rolling broken, the straight, outside the straight, separated layer, scar, pits, convex package, Ma Hang (Ma) , The spiral Road, outside the spiral Road, Green Line, correction concave, such as roller. Crack, slight internal and external straight, minor internal and external spiral, straightening, and so
on. In addition to the internal and external cracks, cracks, broken, rolling, Concave, roll as a general defect.
4, Physical and chemical properties
Including mechanical properties at room temperature and mechanical properties at certain temperatures (heat and low temperature properties) and corrosion resistance (such as anti-oxidation, water erosion, acid and alkali resistance and other properties) under normal circumstances depends on the chemical composition of steel, Performance and steel purity and steel heat treatment methods. In some cases, the rolling temperature and the degree of deformation of the steel pipe will also affect the performance of the steel pipe.
5, Process performance
Including flaring, flattening, crimping, bending, pulling and welding performance.
6, Microstructure
Including the low-power steel pipe and high-power organization.
7, Special requirements
In the user's use of steel pipe other than the standard requirements.
2016年10月27日星期四
Difference between Straight Seam Welded Pipe and Spiral Welded Pipe and the Ways of Derusting
Longitudinal and spiral welded pipe is the main difference between the two different production processes, first of all, the formation of straight seam welded pipe is the first through the molding machine to form hot rolled coil, making it into a cylindrical cylindrical outer surface, and then Welding, welding using the proximity effect or under the flux layer of the arc and skin effect, heating the edge of the tube and make it melt, in the appropriate extrusion cooling forming. Longitudinal submerged arc welded pipe and high-frequency straight seam welded pipe is different from the edge of the tube melting differentiate, the general use of arc melting is called the straight seam submerged arc welded pipe, high frequency straight seam welded pipe is the use of high frequency current melting. Spiral welded pipe production process is first in accordance with the appropriate angle of the spiral low-carbon structural steel and low carbon steel coil into the tube, and then welded seam molding. Spiral submerged arc welded pipe is the main form of spiral welded pipe. Can use the narrow steel billets to produce large diameter steel pipe is the most significant feature of the spiral pipe, widely used in all walks of life in China's gas pipeline construction.
To reduce the coating quality, layer type and the construction of environmental factors on the life of straight seam welded pipe coating life, regular welding of straight pipe to rust. Common methods of descaling are four, namely, pickling, cleaning, spray derusting and tool rust. Pickling is one of the most commonly used methods of derusting, not only as a reprocessing process after sand blasting, but also the surface of the straight seam welded pipe rust, oxide, worn coating completely removed, although this cleaning method can make steel surface roughness and cleanliness are up to standard requirements, but after all, is a chemical cleaning method, the surrounding environment is likely to cause pollution. Straight seam steel pipe cleaning can only be used as an auxiliary means in the anti-corrosion treatment, because the cleaning method can only steel surface dust, grease, and lubricants and other residual organic matter removed, and can not play a preservative effect, as we usually wash their hands , You can clean the surface of the dirt, most of the bacteria still remain in the hand. Professional and technical personnel with steel wire brush and other cleaning tools to polish the surface of the workpiece, this approach is called tool rust, loose rust, welding slag and oxide, etc. can be completely removed, but the steel surface attached to the solid Scale is powerless, can not achieve the standard anti-corrosion effect. Spray derusting is the use of steel grit, steel balls and other high-quality abrasive material through the jet strong centrifugal force to the surface of straight seam steel pipe to spray, not only can effectively remove the surface dirt, rust and oxides, roughness will be abrasive And the longitudinal welded pipe friction under the standard level.
To reduce the coating quality, layer type and the construction of environmental factors on the life of straight seam welded pipe coating life, regular welding of straight pipe to rust. Common methods of descaling are four, namely, pickling, cleaning, spray derusting and tool rust. Pickling is one of the most commonly used methods of derusting, not only as a reprocessing process after sand blasting, but also the surface of the straight seam welded pipe rust, oxide, worn coating completely removed, although this cleaning method can make steel surface roughness and cleanliness are up to standard requirements, but after all, is a chemical cleaning method, the surrounding environment is likely to cause pollution. Straight seam steel pipe cleaning can only be used as an auxiliary means in the anti-corrosion treatment, because the cleaning method can only steel surface dust, grease, and lubricants and other residual organic matter removed, and can not play a preservative effect, as we usually wash their hands , You can clean the surface of the dirt, most of the bacteria still remain in the hand. Professional and technical personnel with steel wire brush and other cleaning tools to polish the surface of the workpiece, this approach is called tool rust, loose rust, welding slag and oxide, etc. can be completely removed, but the steel surface attached to the solid Scale is powerless, can not achieve the standard anti-corrosion effect. Spray derusting is the use of steel grit, steel balls and other high-quality abrasive material through the jet strong centrifugal force to the surface of straight seam steel pipe to spray, not only can effectively remove the surface dirt, rust and oxides, roughness will be abrasive And the longitudinal welded pipe friction under the standard level.
Straight Seam Welded Pipe Weld Flaw Detection Method
In order to detect the transverse or longitudinal defect of the weld of LSAW longitudinal seam, ultrasonic testing was carried out by jet (water column) coupling. Jet (water column) ultrasonic flaw detection is the probe and the pipe through the jet coupling between the probe issued by the longitudinal wave beam through the water or steel interface into the steel pipe, through the waveform conversion of the steel pipe welds pure shear wave detection.
Therefore, the realization of the weld in the pure shear wave detection, the probe angle of incidence must be between the critical angle and the critical angle between the II, can be derived from the law of refraction. The critical angles of the first and second critical angles of incident longitudinal waves from the water to steel are calculated to be 14.5 °and 27.3 °, respectively.
Longitudinal welded pipe Ultrasonic Inspection: Nondestructive testing is on-site testing, fast and non-destructive, without the need to arrive at the laboratory, greatly improving efficiency. The analysis speed is much faster than a benchtop spectrometer, and the results are displayed in seconds. Small size, light weight, easy to carry.
There are many kinds of nondestructive testing of ultrasonic flaw detection. The flaw detection principle of longitudinal seam welded pipe is not divided into: ultrasonic flaw detection, X-ray flaw detection and film flaw detection. Detection methods are: single-sided double-sided flaw detection, double-sided double-sided flaw detection, single-sided detection.
Therefore, the realization of the weld in the pure shear wave detection, the probe angle of incidence must be between the critical angle and the critical angle between the II, can be derived from the law of refraction. The critical angles of the first and second critical angles of incident longitudinal waves from the water to steel are calculated to be 14.5 °and 27.3 °, respectively.
Longitudinal welded pipe Ultrasonic Inspection: Nondestructive testing is on-site testing, fast and non-destructive, without the need to arrive at the laboratory, greatly improving efficiency. The analysis speed is much faster than a benchtop spectrometer, and the results are displayed in seconds. Small size, light weight, easy to carry.
There are many kinds of nondestructive testing of ultrasonic flaw detection. The flaw detection principle of longitudinal seam welded pipe is not divided into: ultrasonic flaw detection, X-ray flaw detection and film flaw detection. Detection methods are: single-sided double-sided flaw detection, double-sided double-sided flaw detection, single-sided detection.
2016年10月25日星期二
Anti-corrosion Measures of Oil Casing
Oil casing is the lifeline to maintain the normal operation of oil wells. Because of the different geological conditions, the stress state of the underground is complex, and the tensile, compressive, bending and torsional stresses act on the pipe body together, and the crude oil contains a lot of corrosive substances, and the oil casing is very easy to produce the corrosion. There are some anti-corrosion measures of oil casing following below:
1, Do a good job of water quality standards, strict water quality testing and management. The implementation of clean-up sub-injection, strengthening the main water pipe cleaning work, so that the station, the bottom of water quality standards, to reduce the introduction of corrosion space annular space.
2. Put into operation for the new injection wells, to take the main sterilization to vote for the ring to protect the liquid, and the formation of regular investment dosing.
3. In view of the mechanical abrasion to accelerate the role of corrosion of oil casing, it is recommended in the tubing coupling with a rubber ring or a serious deviation in the well plus a centralizer, to avoid the process and the process of water injection pipe casing and One side contact sleeve.
4. For serious bacteria corrosion and high temperature SRB slow growth and kill the situation, can be periodically injected into the annulus of 100 degrees Celsius high temperature water or water vapor to kill the SRB under the scale. Share from the Hebei Xin joint oil tube.
5. It is not recommended to promote cathodic protection and catalog casing before corrosion in the casing of injection wells is not effectively controlled.
6. You can brush the oil inside and outside the casing wall layer of anti-corrosion coating.
1, Do a good job of water quality standards, strict water quality testing and management. The implementation of clean-up sub-injection, strengthening the main water pipe cleaning work, so that the station, the bottom of water quality standards, to reduce the introduction of corrosion space annular space.
2. Put into operation for the new injection wells, to take the main sterilization to vote for the ring to protect the liquid, and the formation of regular investment dosing.
3. In view of the mechanical abrasion to accelerate the role of corrosion of oil casing, it is recommended in the tubing coupling with a rubber ring or a serious deviation in the well plus a centralizer, to avoid the process and the process of water injection pipe casing and One side contact sleeve.
4. For serious bacteria corrosion and high temperature SRB slow growth and kill the situation, can be periodically injected into the annulus of 100 degrees Celsius high temperature water or water vapor to kill the SRB under the scale. Share from the Hebei Xin joint oil tube.
5. It is not recommended to promote cathodic protection and catalog casing before corrosion in the casing of injection wells is not effectively controlled.
6. You can brush the oil inside and outside the casing wall layer of anti-corrosion coating.
Causes of Hot Rolling Cracks in N80Q Oil Casing
Hot-rolled seamless steel pipe production is one of the important processes, the rational development of its process plan or not, a direct impact on the size of the steel pipe after rolling the surface of the precision and quality,
Unreasonable process plan will cause the inner surface of the steel pipe to produce the defects such as folding, crack and concave.
N80Q steel casing is a standard oil casing commonly used in oil (for the seamless steel pipe), the standard provisions of the finished pipe heat treatment process for quenching and tempering.
N80Q casing production process is as follows: furnace refining → continuous casting → annular furnace → perforation → continuous rolling → stepping furnace → sizing → sawing → tempering treatment → straightening → physical and chemical testing → testing → thread processing → Coupling tight → water pressure test → measuring length weighing, marking → packaging storage. The billet was heated in an annular furnace for about 2.5 hours, perforated at about 1250 °C and then subjected to continuous rolling. The sintering temperature was 950 °C and the finish rolling temperature was 900 °C. The chemical composition of the tube from the test results can know the chemical composition of the tube is not the cause of the formation of cracks. From the metallographic, The results of EDS analysis show that both the crack tip and the middle part contain iron oxide inclusions. The crack is a non-quenching crack and should be produced before the heat treatment. This is probably caused by the perforation and hot rolling of the steel tube.
In the process of perforation of steel pipe, because temperature non-uniformity and uneven deformation have a large additional stress, the blank in the perforation easy to crack; And the heating temperature is too high, will also be due to reduce the intergranular binding force cracks; if the heating temperature is too low, due to lower plasticity, deformation resistance and deterioration of the perforation conditions, will also crack. In addition, the perforation process, due to the presence of additional deformation, when the billet surface will produce longitudinal shear stress and transverse shear shear stress. Therefore, there is a large lateral and longitudinal additional stress in the outer layer of the steel tube. In the case of non-uniform heating of the tube, when the superposition of the transverse basic stress and the additional tensile stress exceeds the intergranular bonding force, Small cracks, these cracks in the subsequent rolling and sizing process, along the rolling direction is elongated and extended to form the final crack. Therefore, in the future production should pay special attention to the perforation temperature, sizing temperature and finishing temperature of the monitoring and control, as far as possible the temperature fluctuations in the control within ± 20 ℃, and should increase the light tube end of the test strength, If necessary, increase the cut length of the pipe end.
N80Q casing pipe end crack is in the steel pipe perforation and rolling process; when the billet is hole, due to uneven heating temperature, at the same time in the transverse and longitudinal additional stress, resulting in crack formation and expansion.
It is suggested to adjust the process parameters of perforation and hot rolling in time, strengthen the control of the tube heating temperature, making the tube heating temperature fluctuations in a reasonable range.
Unreasonable process plan will cause the inner surface of the steel pipe to produce the defects such as folding, crack and concave.
N80Q steel casing is a standard oil casing commonly used in oil (for the seamless steel pipe), the standard provisions of the finished pipe heat treatment process for quenching and tempering.
N80Q casing production process is as follows: furnace refining → continuous casting → annular furnace → perforation → continuous rolling → stepping furnace → sizing → sawing → tempering treatment → straightening → physical and chemical testing → testing → thread processing → Coupling tight → water pressure test → measuring length weighing, marking → packaging storage. The billet was heated in an annular furnace for about 2.5 hours, perforated at about 1250 °C and then subjected to continuous rolling. The sintering temperature was 950 °C and the finish rolling temperature was 900 °C. The chemical composition of the tube from the test results can know the chemical composition of the tube is not the cause of the formation of cracks. From the metallographic, The results of EDS analysis show that both the crack tip and the middle part contain iron oxide inclusions. The crack is a non-quenching crack and should be produced before the heat treatment. This is probably caused by the perforation and hot rolling of the steel tube.
In the process of perforation of steel pipe, because temperature non-uniformity and uneven deformation have a large additional stress, the blank in the perforation easy to crack; And the heating temperature is too high, will also be due to reduce the intergranular binding force cracks; if the heating temperature is too low, due to lower plasticity, deformation resistance and deterioration of the perforation conditions, will also crack. In addition, the perforation process, due to the presence of additional deformation, when the billet surface will produce longitudinal shear stress and transverse shear shear stress. Therefore, there is a large lateral and longitudinal additional stress in the outer layer of the steel tube. In the case of non-uniform heating of the tube, when the superposition of the transverse basic stress and the additional tensile stress exceeds the intergranular bonding force, Small cracks, these cracks in the subsequent rolling and sizing process, along the rolling direction is elongated and extended to form the final crack. Therefore, in the future production should pay special attention to the perforation temperature, sizing temperature and finishing temperature of the monitoring and control, as far as possible the temperature fluctuations in the control within ± 20 ℃, and should increase the light tube end of the test strength, If necessary, increase the cut length of the pipe end.
N80Q casing pipe end crack is in the steel pipe perforation and rolling process; when the billet is hole, due to uneven heating temperature, at the same time in the transverse and longitudinal additional stress, resulting in crack formation and expansion.
It is suggested to adjust the process parameters of perforation and hot rolling in time, strengthen the control of the tube heating temperature, making the tube heating temperature fluctuations in a reasonable range.
2016年9月28日星期三
The Relativity Weld Heat Affected Zone and Welded Pipe Quality of ERW Welded Pipe
The quality of welded pipe depends on the quality of welding. The quality of welding is not only directly related to the quality of the tube, especially with the design of the forming roll, the forming process, the choice of welding parameters. These factors with the equipment to adjust the state and the rapidly changing, only by visual inspection of welding sparks, shavings and simple flaring state, flattening test and other empirical methods of control, it is difficult to maintain a stable quality.
The shape and width of the weld affected zone are closely related to the welding speed, temperature, extrusion force and even tube thickness. When the welding speed constant, the heat affected zone width and welding temperature is proportional to (ie, the higher the temperature, the width of the larger), and inversely proportional to the extrusion force (ie, the greater the extrusion pressure, the smaller the width); when squeeze (Ie, the higher the temperature, the greater the width), and inversely proportional to the welding speed (that is, the faster the faster the width of the smaller); when the welding temperature does not change, the heat-affected zone width is proportional to the welding temperature, The width of the heat-affected zone is inversely proportional to the extrusion force (ie, the larger the squeezing force and the smaller the width), and is inversely proportional to the welding speed (ie, the faster the width and the smaller the width). Thus, the welding process should be welded within the scope of safety, fully explore the potential of pipe equipment, according to the wall thickness of the tube, the rational allocation of induction coil position and the size of the opening angle to ensure adequate heat output conditions, and gradually increase the welding Speed, the appropriate extrusion force to make the formation of the ideal heat affected zone shape, and in this state stable operation, the welding quality will be able to steadily improve.
The shape and width of the weld affected zone are closely related to the welding speed, temperature, extrusion force and even tube thickness. When the welding speed constant, the heat affected zone width and welding temperature is proportional to (ie, the higher the temperature, the width of the larger), and inversely proportional to the extrusion force (ie, the greater the extrusion pressure, the smaller the width); when squeeze (Ie, the higher the temperature, the greater the width), and inversely proportional to the welding speed (that is, the faster the faster the width of the smaller); when the welding temperature does not change, the heat-affected zone width is proportional to the welding temperature, The width of the heat-affected zone is inversely proportional to the extrusion force (ie, the larger the squeezing force and the smaller the width), and is inversely proportional to the welding speed (ie, the faster the width and the smaller the width). Thus, the welding process should be welded within the scope of safety, fully explore the potential of pipe equipment, according to the wall thickness of the tube, the rational allocation of induction coil position and the size of the opening angle to ensure adequate heat output conditions, and gradually increase the welding Speed, the appropriate extrusion force to make the formation of the ideal heat affected zone shape, and in this state stable operation, the welding quality will be able to steadily improve.
Application and Management of High Frequency Welding Machine in ERW Weld Pipeline
In the caliber of longitudinal welded pipe production line is set welding, finishing, pipe processing, pipe casing heat treatment in one of the pipe production line. ERW steel pipe line which introduced the German SMS Meer company developed molding equipment and technology, and equipped with the world's most advanced non-destructive testing equipment, high-frequency welding equipment, heat treatment of welding equipment.
The welding of forming steel pipe is the core part of welded pipe line, the quality of welding directly determines the qualified rate of the product. With the power components and power electronics technology continues to develop, as well as heating, melting, welding equipment to promote the demand for induction, induction welding equipment technology has also been an unprecedented opportunity for development. Power components from the tube to the SCR, MOSFET to IGBT gradually adopted, induction device power, frequency is also gradually increased.
ERW pipe unit has absorbed the development experience of similar units in the world, combined with the development of the world's advanced high-frequency induction technology, using EFD IGBT-based high-power high-frequency induction welding technology. The device can be used as induction welder, can also replace the load into contact welding machine. The advantages of contact welding is high efficiency, low power consumption, but its drawback is easy to leave contact block scratches and EDM burn marks. Therefore, in view of the user's quality requirements of the continuous improvement of high-frequency induction welding in the 20th century, 90 years has been a great application.
The welding principle of the contact welding is basically the same as that of the induction welding. The difference is that the induction welding requires the coil to be set on the forming steel pipe, and the contact welding is pressing the two edges of the steel strip through the contact shoe. Induction welding current is a high-frequency current through the coil out of the current induction, and contact welding current is the direct use of high-frequency power supply current. Therefore, the contact welding efficiency is significantly higher than the induction welding, but also easy to produce contact scratches and spark burn marks.
The welding of forming steel pipe is the core part of welded pipe line, the quality of welding directly determines the qualified rate of the product. With the power components and power electronics technology continues to develop, as well as heating, melting, welding equipment to promote the demand for induction, induction welding equipment technology has also been an unprecedented opportunity for development. Power components from the tube to the SCR, MOSFET to IGBT gradually adopted, induction device power, frequency is also gradually increased.
ERW pipe unit has absorbed the development experience of similar units in the world, combined with the development of the world's advanced high-frequency induction technology, using EFD IGBT-based high-power high-frequency induction welding technology. The device can be used as induction welder, can also replace the load into contact welding machine. The advantages of contact welding is high efficiency, low power consumption, but its drawback is easy to leave contact block scratches and EDM burn marks. Therefore, in view of the user's quality requirements of the continuous improvement of high-frequency induction welding in the 20th century, 90 years has been a great application.
The welding principle of the contact welding is basically the same as that of the induction welding. The difference is that the induction welding requires the coil to be set on the forming steel pipe, and the contact welding is pressing the two edges of the steel strip through the contact shoe. Induction welding current is a high-frequency current through the coil out of the current induction, and contact welding current is the direct use of high-frequency power supply current. Therefore, the contact welding efficiency is significantly higher than the induction welding, but also easy to produce contact scratches and spark burn marks.
2016年9月27日星期二
Welding Defects of High Frequency Welded Pipe and Its Analysis
High frequency straight seam welded steel pipe（hfw steel pipe) welding quality defects are cracks, welding, water leakage, scratches and so on.
First, cracks
Fracture is the main defect of welded pipe, its manifestation can be by the usual cracks, local periodic cracks, irregular intermittent cracks. Some of the steel pipe after welding surface without cracks, but by the flattening,
straightening or hydrostatic test cracks. Severe leakage will leak. There are many causes of cracks. Elimination of cracks is one of the most difficult problems in welding adjustment operations.
Second, take the welding
Lap welding is the edge of the tube in the welding when the dislocation, although the curette can still see the traces of dislocation.
1) Molding quality is not good. Forming the edge of the tube is not usually appear on both sides of the usual lap welding, forming the edge of the wave and the drum package, the local small lap.
2) The production of thin-walled tube, the squeeze pressure properly, easily lead to drought. In the squeeze roll hole type center tube inside the installation of a small roller, can effectively overcome the thin-walled pipe lap welding.
3) Extrusion roller installation uneven, a high and one low, resulting in welding.
4) Strip edge slitting bad, curling or edge burr is too large, resulting in lap welding.
5) Forming vertical roller, horizontal roller and squeeze roll rolling center line is not a straight line, or a sickle with steel bends, resulting in unstable molding, weld reverse, resulting in lap welding.
6) When the position of the front end of the resistor is just at the center of the squeeze roll, the flaring strength value and the crushing strength value are the best. When the center line than the extrusion roller, stretching to the sizer side, the flaring strength and crush strength are significantly reduced. When less than the center line in the molding machine side, but also reduce the welding strength
First, cracks
Fracture is the main defect of welded pipe, its manifestation can be by the usual cracks, local periodic cracks, irregular intermittent cracks. Some of the steel pipe after welding surface without cracks, but by the flattening,
straightening or hydrostatic test cracks. Severe leakage will leak. There are many causes of cracks. Elimination of cracks is one of the most difficult problems in welding adjustment operations.
Second, take the welding
Lap welding is the edge of the tube in the welding when the dislocation, although the curette can still see the traces of dislocation.
1) Molding quality is not good. Forming the edge of the tube is not usually appear on both sides of the usual lap welding, forming the edge of the wave and the drum package, the local small lap.
2) The production of thin-walled tube, the squeeze pressure properly, easily lead to drought. In the squeeze roll hole type center tube inside the installation of a small roller, can effectively overcome the thin-walled pipe lap welding.
3) Extrusion roller installation uneven, a high and one low, resulting in welding.
4) Strip edge slitting bad, curling or edge burr is too large, resulting in lap welding.
5) Forming vertical roller, horizontal roller and squeeze roll rolling center line is not a straight line, or a sickle with steel bends, resulting in unstable molding, weld reverse, resulting in lap welding.
6) When the position of the front end of the resistor is just at the center of the squeeze roll, the flaring strength value and the crushing strength value are the best. When the center line than the extrusion roller, stretching to the sizer side, the flaring strength and crush strength are significantly reduced. When less than the center line in the molding machine side, but also reduce the welding strength
ERW Pipe Production Process and Rolling Groove Processing Principle
At present, ordinary fluid on the market with the general Longitudinal Welded Pipe is generally used in high-frequency resistance welding production, which is characterized by high production efficiency, weld heat affected zone is small, low quality requirements on the bonding surface, but the molding quality requirements, forming process Any change in the shape of the V-shaped opening may cause welding quality problems.
Rolling groove processing is the use of grooved joints as pipe fittings when the pipe pretreatment process. Its operating principle is the use of roll groove rolling machine driven rotating pipe, pipe radial direction of the follow-up pressure roller radial pressure applied to the use of the structure of the pressure roller welded pipe in a fixed position of cold out a specified groove.
A "roll groove cracking" is the root cause of the weld strength is not enough, coupled with rolling groove processing of the severe deformation, resulting in weld stress concentration and tear. Raw material is the source of product quality, production must master its characteristics. From the welding point of view, the impact of raw materials on the quality of the weld is mainly reflected in the welding of the material and the two aspects of organization. Elements
of alloying elements and the morphology of the weld quality also affect. The high content of sulfur and phosphorus in the material will easily cause crystallization segregation; the high carbon content will promote the formation of martensite, the embrittlement of the weld metal; the grain size of the metal structure is too large, the direction of the weld crystal will be strengthened; Easy to promote the segregation of impurities. There are non-metallic materials in the inclusion, stratification, width and thickness fluctuations, all kinds of factors may cause weld cracks and reduce weld strength.
ERW steel pipe main welding process parameters are input power, raw production speed, opening angle, welding pressure, induction coil (induction contact) and the location of the impedance and so on. The unreasonable setting of welding
parameters is an important reason for the phenomenon of rolling groove cracking. If the input power is not enough, the speed is too fast, the input heat is insufficient, the edge of the steel strip is not completely melted, the end solid oxide can not be extruded out to form the low-temperature welding defect; conversely, the input heat is too large, , Metal splash and return inclusions and other defects. Secondly, the welding pressure is also important. If the welding
pressure is not enough, the fusion line on both sides of the metal microstructure flow line is not obvious, welding strength will not meet the requirements; the other hand, the welding pressure is too large, irregular weld lines, metal
flow line rise angle is too large, Reduced only when the welding pressure is appropriate should be, the fusion line without distortion, metal streamline angle of 45 °~ 60 °ideal state, the weld strength is guaranteed.
Rolling groove processing is the use of grooved joints as pipe fittings when the pipe pretreatment process. Its operating principle is the use of roll groove rolling machine driven rotating pipe, pipe radial direction of the follow-up pressure roller radial pressure applied to the use of the structure of the pressure roller welded pipe in a fixed position of cold out a specified groove.
A "roll groove cracking" is the root cause of the weld strength is not enough, coupled with rolling groove processing of the severe deformation, resulting in weld stress concentration and tear. Raw material is the source of product quality, production must master its characteristics. From the welding point of view, the impact of raw materials on the quality of the weld is mainly reflected in the welding of the material and the two aspects of organization. Elements
of alloying elements and the morphology of the weld quality also affect. The high content of sulfur and phosphorus in the material will easily cause crystallization segregation; the high carbon content will promote the formation of martensite, the embrittlement of the weld metal; the grain size of the metal structure is too large, the direction of the weld crystal will be strengthened; Easy to promote the segregation of impurities. There are non-metallic materials in the inclusion, stratification, width and thickness fluctuations, all kinds of factors may cause weld cracks and reduce weld strength.
ERW steel pipe main welding process parameters are input power, raw production speed, opening angle, welding pressure, induction coil (induction contact) and the location of the impedance and so on. The unreasonable setting of welding
parameters is an important reason for the phenomenon of rolling groove cracking. If the input power is not enough, the speed is too fast, the input heat is insufficient, the edge of the steel strip is not completely melted, the end solid oxide can not be extruded out to form the low-temperature welding defect; conversely, the input heat is too large, , Metal splash and return inclusions and other defects. Secondly, the welding pressure is also important. If the welding
pressure is not enough, the fusion line on both sides of the metal microstructure flow line is not obvious, welding strength will not meet the requirements; the other hand, the welding pressure is too large, irregular weld lines, metal
flow line rise angle is too large, Reduced only when the welding pressure is appropriate should be, the fusion line without distortion, metal streamline angle of 45 °~ 60 °ideal state, the weld strength is guaranteed.
Cold Pressure Welding
Cold pressure welding, at room temperature conditions, with the help of the metal to be welded to produce plastic deformation and solid-state welding method. Pressure deformation, the workpiece contact surface of the oxide film is destroyed and squeezed out, so that pure metal contacts to achieve intergranular bonding, to clean the welded joints. The applied pressure is generally higher than the yield strength of the material to produce 60 to 90% of the deformation. Pressing method can be slow extrusion, rolling or impact, can also be divided into several times to achieve the required amount of deformation.
The main technical parameters of welding are determined by the mold size, so it is easy to operate and automation, the welding quality is stable, the productivity is high, the cost is low; Do not use flux, the joint will not cause corrosion. ; Welding joint temperature does not rise, the material crystalline state unchanged, especially for dissimilar metals and heat welding can not be achieved in a number of metal materials and products welding. Cold welding has become the electrical industry, aluminum products and space welding the most important in the field of one of several limited welding methods.
Cold presses and the surface of the die may accumulate metal debris, must be regularly removed. If compressed air, compressed air can be used to blow off the debris. If you want to completely remove the debris, you can remove the mold from the welder, the mold of the four modules apart, with a magnifying glass carefully each module to ensure that all the surface of the module trace debris have been cleared. Mold removal must be careful, especially small springs easy to lose. The unclean surface of the mold will cause the wires to slip easily in the mold, so that the welding fails. Note that the mold after the maintenance of the work surface must not allow any grease.
The main technical parameters of welding are determined by the mold size, so it is easy to operate and automation, the welding quality is stable, the productivity is high, the cost is low; Do not use flux, the joint will not cause corrosion. ; Welding joint temperature does not rise, the material crystalline state unchanged, especially for dissimilar metals and heat welding can not be achieved in a number of metal materials and products welding. Cold welding has become the electrical industry, aluminum products and space welding the most important in the field of one of several limited welding methods.
Cold presses and the surface of the die may accumulate metal debris, must be regularly removed. If compressed air, compressed air can be used to blow off the debris. If you want to completely remove the debris, you can remove the mold from the welder, the mold of the four modules apart, with a magnifying glass carefully each module to ensure that all the surface of the module trace debris have been cleared. Mold removal must be careful, especially small springs easy to lose. The unclean surface of the mold will cause the wires to slip easily in the mold, so that the welding fails. Note that the mold after the maintenance of the work surface must not allow any grease.
Cold Welding
Cold welding is the application of mechanical force, molecular force or power to make welding material diffusion to the surface of a process equipment (method). At the microscopic scale, this phenomenon is closely related to the diffusion of atoms on the surface of the material.
Cold welding machine can be divided into welding, cold welding machine, paste-type repair of cold welding, welding copper and aluminum wire cold welding machine. The former two are used to repair metal, casting surface wear, scratches, porosity, trachoma and other small defects; the latter for welding copper wire, aluminum and other non-ferrous metal wire, such as motor welding enameled wire.
Due to the cold welding difference and the traditional sense of welding, cold solder hardness, adhesion and strength is particularly high, almost no shrinkage, can reliably prevent many chemical effects, physical stress and mechanical stress, it is also called "liquid metal". The use of reasonable technology, select the appropriate chemical bonding materials (adhesives, sealants, retaining agent, repair agent, etc.) will be the same material or dissimilar materials connected together to achieve connectivity, sealing, holding, functional coating, One of the main applications currently.
Cold welding can be used for all metals and almost all other raw materials to connect with each other, fixed welding and sealing, hardening and metal can file, planing, grinding, milling, polishing, cars, shot peening, Kinds of tools for processing. For the repair of old equipment, to reduce the manufacturing process of waste defective, is of great significance. Moreover, the connection of some materials with the general welding method, because the welding temperature is high, not only detrimental to the strength of the material, but also easy to deformation, especially for thin material even more problematic. However, these problems do not exist for cold welding, because the cold welding is carried out at room temperature, while the stress of the joints can be more evenly distributed in all the plastic surface, thereby improving the metal due to welding, riveting, bolting caused by Of the above part of the problem, increased fatigue life.
With the application of cold welding technology is mature, polymer composites cold welding applications are more stable and widespread, and nano-materials between the cold welding is gaining more and more attention, including nano-assembly and advanced manufacturing, biosensor, the next Generation microelectronic components and chip interconnect technology.
Cold welding machine can be divided into welding, cold welding machine, paste-type repair of cold welding, welding copper and aluminum wire cold welding machine. The former two are used to repair metal, casting surface wear, scratches, porosity, trachoma and other small defects; the latter for welding copper wire, aluminum and other non-ferrous metal wire, such as motor welding enameled wire.
Due to the cold welding difference and the traditional sense of welding, cold solder hardness, adhesion and strength is particularly high, almost no shrinkage, can reliably prevent many chemical effects, physical stress and mechanical stress, it is also called "liquid metal". The use of reasonable technology, select the appropriate chemical bonding materials (adhesives, sealants, retaining agent, repair agent, etc.) will be the same material or dissimilar materials connected together to achieve connectivity, sealing, holding, functional coating, One of the main applications currently.
Cold welding can be used for all metals and almost all other raw materials to connect with each other, fixed welding and sealing, hardening and metal can file, planing, grinding, milling, polishing, cars, shot peening, Kinds of tools for processing. For the repair of old equipment, to reduce the manufacturing process of waste defective, is of great significance. Moreover, the connection of some materials with the general welding method, because the welding temperature is high, not only detrimental to the strength of the material, but also easy to deformation, especially for thin material even more problematic. However, these problems do not exist for cold welding, because the cold welding is carried out at room temperature, while the stress of the joints can be more evenly distributed in all the plastic surface, thereby improving the metal due to welding, riveting, bolting caused by Of the above part of the problem, increased fatigue life.
With the application of cold welding technology is mature, polymer composites cold welding applications are more stable and widespread, and nano-materials between the cold welding is gaining more and more attention, including nano-assembly and advanced manufacturing, biosensor, the next Generation microelectronic components and chip interconnect technology.
2016年9月26日星期一
Seamless Steel Product By Application
Classfication of seamless steel pipe by application
1. Line pipe.
Such as: water, gas pipes, steam pipes seamless pipe, oil pipeline, oil and gas line pipe. Agricultural irrigation faucet with pipes and sprinkler pipe.
2. Thermal equipment tube.
Such as general boiler boiling water pipe, superheated steam pipes, locomotive boiler superheater tubes, opium pipe, small pipe, brick arch pipe and high-temperature high-pressure boiler tubes.
3. Mechanical industrial pipe.
Such as aviation structural tube (tube, oval tube, flat oval tube), automobile axle tube, axle tubes, structural tubes automobile and tractor, tractor oil cooler tube, farm with a square tube and rectangular tube, transformer tube and bearing tubes.
4. Petroleum geological drilling pipe.
Such as: oil drilling pipe, drill pipe (Kelly and hexagonal drill), drill collar, oil tubing, casing and various fittings, geological drilling pipe (core pipe, casing, active drill pipe, drill collar press hoop and pin connectors, etc.).
5. Chemical industrial pipe.
Such as: petroleum cracking tube, chemical equipment, pipes and tube heat exchangers, acid-resistant stainless pipe, fertilizer use and transport chemical medium pressure pipe with a pipe.
6. Other departments tube.
Such as: container tube (high pressure gas cylinder pipe and tube container ships), instrumentation tube, watch shell tube, needles and tubes and other medical devices.
1. Line pipe.
Such as: water, gas pipes, steam pipes seamless pipe, oil pipeline, oil and gas line pipe. Agricultural irrigation faucet with pipes and sprinkler pipe.
2. Thermal equipment tube.
Such as general boiler boiling water pipe, superheated steam pipes, locomotive boiler superheater tubes, opium pipe, small pipe, brick arch pipe and high-temperature high-pressure boiler tubes.
3. Mechanical industrial pipe.
Such as aviation structural tube (tube, oval tube, flat oval tube), automobile axle tube, axle tubes, structural tubes automobile and tractor, tractor oil cooler tube, farm with a square tube and rectangular tube, transformer tube and bearing tubes.
4. Petroleum geological drilling pipe.
Such as: oil drilling pipe, drill pipe (Kelly and hexagonal drill), drill collar, oil tubing, casing and various fittings, geological drilling pipe (core pipe, casing, active drill pipe, drill collar press hoop and pin connectors, etc.).
5. Chemical industrial pipe.
Such as: petroleum cracking tube, chemical equipment, pipes and tube heat exchangers, acid-resistant stainless pipe, fertilizer use and transport chemical medium pressure pipe with a pipe.
6. Other departments tube.
Such as: container tube (high pressure gas cylinder pipe and tube container ships), instrumentation tube, watch shell tube, needles and tubes and other medical devices.
Seamless Steel Pipe Connection
Seamless steel pipe connection is following below:
Pipe coupling according to the pipe end can be divided into: light pipe (pipe end without threads) and threading pipe (pipe end threaded).
Car wire tube is divided into: general threading pipe and threading pipe end upsetting.
Thick threading pipe can be divided into: EUE (with external thread), internal upset (with internal thread) and internal and external thickening (with external threads), etc. threading pipe.
If you press threading pipe thread type can be divided into: ordinary cylindrical or conical screw thread and other places of special threading pipe. In addition, according to user needs, threading pipe is generally equipped with fittings delivery.
Pipe coupling according to the pipe end can be divided into: light pipe (pipe end without threads) and threading pipe (pipe end threaded).
Car wire tube is divided into: general threading pipe and threading pipe end upsetting.
Thick threading pipe can be divided into: EUE (with external thread), internal upset (with internal thread) and internal and external thickening (with external threads), etc. threading pipe.
If you press threading pipe thread type can be divided into: ordinary cylindrical or conical screw thread and other places of special threading pipe. In addition, according to user needs, threading pipe is generally equipped with fittings delivery.
2016年9月24日星期六
Tips of Improving Straight Seam Steel Pipe Surface Wall Thickness
1, Tube heating
The average heating to stop the rapid rise and fall of temperature. To adhere to a smooth landing every time the temperature slowly, the temperature does not exceed the maximum landing 30 ℃.
2, Mandrel mill
The average wall thickness of the thick-walled tubes and solid billets, so that the probability of a significant reduction in the mandrel bending deformation, can be useful for the progress of the wall thickness precision steel pipe.
3, Precision of the mandrel
Mandrel outer precision control at ± 0.1mm, straight degrees mandrel deflection does not exceed 5mm. Welding, finishing pierce a pin positioned between two sections of the mandrel, in order to avoid the formation of solder total straightness deviation is too large.
4, Perfect process
Perfect process, to avoid the center and pull the thin wall thickness by Haou transcend the limitations of the control condition seizures, progressive wall thickness accuracy.
5, Centering rollers
Determining whether the centering roller assembly in place, adjust the rollers hold the central core, open angle and various initiatives ashamed size consistent in the middle to hold the core roll rolling line.
6, Piercing mandrel
Normal Select piercing mandrel outer diameter Φ108mm-Φ114mm, wall thickness and wall thickness requirements ≥25mm average of thick-walled tube.
7, Intermediate rolling line
Ensure that punch line and the middle of rolling the car in the middle perforation lines consistent and prevent "rolling on" or "rolling down" so that the tube adhere average force at the time of perforation.
8, Things rolling
Head wear on the guide plate and roller rolling things to change in real time.
9, Rolling means something
Roller distance, middle distance necessary to guide the rolling line. Guarantee and roll away from the guide wire in the middle of the middle of the piercing and rolling line, namely the upper and lower roller pitch equal distance about equal to the guide. In the straight seam steel pipe production process, because the primary process is in a hot state, so the heating operation is resolution product quality is very important process. This operation is the key blank is heated uniformly heated to a temperature suitable for processing.
Heating will be wrong in the outer surface of the tube surface may exhibit cracks, folds and migraine pain and other waste reason. Because a great impact on the quality of the perforation, that is, when the temperature of the process piercing is an important condition affecting the quality, it is generally the temperature of the billet piercing working is to manipulate. The second key is to try to reduce the heating operation scale quantities. Especially in hot kneading the elbow, leaving the surface quality of life several things and kneading pipe, pleading even more severe.
The average heating to stop the rapid rise and fall of temperature. To adhere to a smooth landing every time the temperature slowly, the temperature does not exceed the maximum landing 30 ℃.
2, Mandrel mill
The average wall thickness of the thick-walled tubes and solid billets, so that the probability of a significant reduction in the mandrel bending deformation, can be useful for the progress of the wall thickness precision steel pipe.
3, Precision of the mandrel
Mandrel outer precision control at ± 0.1mm, straight degrees mandrel deflection does not exceed 5mm. Welding, finishing pierce a pin positioned between two sections of the mandrel, in order to avoid the formation of solder total straightness deviation is too large.
4, Perfect process
Perfect process, to avoid the center and pull the thin wall thickness by Haou transcend the limitations of the control condition seizures, progressive wall thickness accuracy.
5, Centering rollers
Determining whether the centering roller assembly in place, adjust the rollers hold the central core, open angle and various initiatives ashamed size consistent in the middle to hold the core roll rolling line.
6, Piercing mandrel
Normal Select piercing mandrel outer diameter Φ108mm-Φ114mm, wall thickness and wall thickness requirements ≥25mm average of thick-walled tube.
7, Intermediate rolling line
Ensure that punch line and the middle of rolling the car in the middle perforation lines consistent and prevent "rolling on" or "rolling down" so that the tube adhere average force at the time of perforation.
8, Things rolling
Head wear on the guide plate and roller rolling things to change in real time.
9, Rolling means something
Roller distance, middle distance necessary to guide the rolling line. Guarantee and roll away from the guide wire in the middle of the middle of the piercing and rolling line, namely the upper and lower roller pitch equal distance about equal to the guide. In the straight seam steel pipe production process, because the primary process is in a hot state, so the heating operation is resolution product quality is very important process. This operation is the key blank is heated uniformly heated to a temperature suitable for processing.
Heating will be wrong in the outer surface of the tube surface may exhibit cracks, folds and migraine pain and other waste reason. Because a great impact on the quality of the perforation, that is, when the temperature of the process piercing is an important condition affecting the quality, it is generally the temperature of the billet piercing working is to manipulate. The second key is to try to reduce the heating operation scale quantities. Especially in hot kneading the elbow, leaving the surface quality of life several things and kneading pipe, pleading even more severe.
Notes of Seamless Steel Pipe Production Process Equipment Points
1. Oiled marking: steel pipe hydrostatic testing machine after passing were oiled to prevent corrosion, and according to user requirements for marking.
2. Leveling milling: the flat steel anvil machine so that the original curl, and then through the edge milling machine for two-sided steel milling, so as to meet the requirements of the plate width, plate edge parallelism and groove shape.
3. Shear molding: the steel plate production line along the outer edge of the spiral curl into a tube.
4. Butt cut: seamless steel pipe market equipment using advanced technology pre double submerged arc welding, internal welding, outside welding. The welded steel pipe using a plasma-foot cut to specification length.
5. Visual inspection: by professional and technical personnel to some of the basic parameters to be checked.
6. The ultrasonic flaw detection: scrap development of the inner and outer sides of the base metal and weld seam 100% inspection.
7. X-ray detection: internal and external welds 100% X-ray industrial TV check image processing system to ensure that the use of detection sensitivity.
8. The pressure test: the steel pipe hydrostatic testing machine shall be tested individually to ensure that the test pressure pipe meet the required standards.
9. Chamfering flat head: seamless steel pipe inspection devices will be qualified after the pipe end processing, to meet the requirements of the pipe end (spiral welded pipe mill) groove dimensions.
10. Final inspection: leveler again ultrasound and X-ray detection as well as magnetic particle inspection pipe end, check if there are problems and welding pipe ends defects.
11. Unwinding board probe: After entering the unwinding plate production line, the first full-board ultrasonic testing.
2. Leveling milling: the flat steel anvil machine so that the original curl, and then through the edge milling machine for two-sided steel milling, so as to meet the requirements of the plate width, plate edge parallelism and groove shape.
3. Shear molding: the steel plate production line along the outer edge of the spiral curl into a tube.
4. Butt cut: seamless steel pipe market equipment using advanced technology pre double submerged arc welding, internal welding, outside welding. The welded steel pipe using a plasma-foot cut to specification length.
5. Visual inspection: by professional and technical personnel to some of the basic parameters to be checked.
6. The ultrasonic flaw detection: scrap development of the inner and outer sides of the base metal and weld seam 100% inspection.
7. X-ray detection: internal and external welds 100% X-ray industrial TV check image processing system to ensure that the use of detection sensitivity.
8. The pressure test: the steel pipe hydrostatic testing machine shall be tested individually to ensure that the test pressure pipe meet the required standards.
9. Chamfering flat head: seamless steel pipe inspection devices will be qualified after the pipe end processing, to meet the requirements of the pipe end (spiral welded pipe mill) groove dimensions.
10. Final inspection: leveler again ultrasound and X-ray detection as well as magnetic particle inspection pipe end, check if there are problems and welding pipe ends defects.
11. Unwinding board probe: After entering the unwinding plate production line, the first full-board ultrasonic testing.
2016年9月23日星期五
Non-destructive Testing of Straight Seam Steel Surface
Surface NDT methods of straight seam steel selection principles: magnetic iron pipe should be used in magnetic particle testing; non-ferromagnetic steel should be used in penetration testing. Delayed cracking tendency of welded joints, the surface should be non-destructive testing after welding cooling certain time; reheat cracking tendency of welded joints, the surface should be in non-destructive testing and post-weld heat treatment once each.
Surface non-destructive testing applications in accordance with the standard requirements that detects objects and applications in general as follows:
(1) An outer surface of the tube material quality inspection.
(2) Important butt weld surface defect detection.
(3) Important fillet surface defect detection.
(4) Important socket weld and jumper tee branch pipe defect detection.
(5) Pipe bending surface defect detection.
(6) The material tends to quench detection larger groove welded joints.
(7) The design temperature is below zero or non-austenitic stainless steel pipe beveling detected 29 degrees Celsius.
(8) The provisions of the double-sided weldment after weld gouging gouging detection
(9) When using oxyacetylene flame cutting jig welded pipes alloy hardening tendency on when grinding parts defect detection.
Surface non-destructive testing applications in accordance with the standard requirements that detects objects and applications in general as follows:
(1) An outer surface of the tube material quality inspection.
(2) Important butt weld surface defect detection.
(3) Important fillet surface defect detection.
(4) Important socket weld and jumper tee branch pipe defect detection.
(5) Pipe bending surface defect detection.
(6) The material tends to quench detection larger groove welded joints.
(7) The design temperature is below zero or non-austenitic stainless steel pipe beveling detected 29 degrees Celsius.
(8) The provisions of the double-sided weldment after weld gouging gouging detection
(9) When using oxyacetylene flame cutting jig welded pipes alloy hardening tendency on when grinding parts defect detection.
Shape Requirements of LSAW Steel Pipe
LSAW steel pipe weld appearance basic requirements:
Straight seam steel pipe before NDT, weld visual inspection should meet the requirements. General requirements for straight seam steel pipe weld appearance and surface quality of welded joints are as follows:
Welding should look good shape, width of each side groove edge 2mm overshadowed appropriate. Fillet weld leg height should meet the design requirements, the shape should be smooth transition.
Welded joint surface requirements:
(1) Does not allow cracks, lack of fusion, pores, slag, spatter exist.
(2) The design temperature is below -29 degrees pipes, stainless steel and hardened alloy steel pipes tend to be larger weld surface, without undercut. Other material pipe weld undercut depth should be greater than 0.5mm, continuous undercut length should not exceed 100mm, and both sides of the weld undercut always grow up to 10 percent of the entire length of the weld.
(3) Shall not be lower than the surface of the weld surface of the pipe. Weld reinforcement and no more than 3mm, (the maximum width of weld joints after groove).
(4) Welded joints the wrong side of the wall thickness should be less than 10% and not more than 2mm.
Straight seam steel pipe before NDT, weld visual inspection should meet the requirements. General requirements for straight seam steel pipe weld appearance and surface quality of welded joints are as follows:
Welding should look good shape, width of each side groove edge 2mm overshadowed appropriate. Fillet weld leg height should meet the design requirements, the shape should be smooth transition.
Welded joint surface requirements:
(1) Does not allow cracks, lack of fusion, pores, slag, spatter exist.
(2) The design temperature is below -29 degrees pipes, stainless steel and hardened alloy steel pipes tend to be larger weld surface, without undercut. Other material pipe weld undercut depth should be greater than 0.5mm, continuous undercut length should not exceed 100mm, and both sides of the weld undercut always grow up to 10 percent of the entire length of the weld.
(3) Shall not be lower than the surface of the weld surface of the pipe. Weld reinforcement and no more than 3mm, (the maximum width of weld joints after groove).
(4) Welded joints the wrong side of the wall thickness should be less than 10% and not more than 2mm.
2016年9月20日星期二
Line Pipe Plate Production
Line pipe used plates 60 to 70 years using the Anshan Iron and Steel and other major manufacturers A3,16Mn, with diameter pipeline delivery pressure increases and progress strength steel can not meet demand. 80 years after each oil pipe plant started by the United States API standard production pipeline steel, because of the domestic pipeline board manufacturing plant immature technology, mainly imported plate. Enter the 1990s, the domestic plate production line developed rapidly, Baosteel, Wuhan Iron and Steel, Anshan, Benxi Iron and Steel, Panzhihua Iron and Steel and other enterprises have developed and produced a series of high-grade steel X pipeline.
In the domestic pipeline steel production process are: a conventional semi-continuous hot rolling, CSP continuous casting and rolling, plate units, Steckel unit.
1) Semi-continuous rolling mill: Includes 1 rack 5 rack Steckel mill and finishing mill. In the semi-continuous rolling mills, strip the finish rolling experienced hot-rolled steel strip from one end to the other end is substantially constant. On finishing mill time between passes is generally less than 3s.
2) CSP continuous casting and rolling: in CSP production line containing niobium, vanadium, titanium composite micro-alloyed carbon steel, the use of appropriate controlled rolling and cooling and coiling process can ensure the mechanical properties and microstructure of steel modern organizations meet the technical requirements of X60 pipeline steel, pipeline steel in line with modern trends. Our CSP continuous casting and rolling production line has been developed to X60 steel, while the United States and other foreign manufacturers CSP has developed and produced high-grade pipeline steel X60, X65 and the X70. Which process is characterized by the presence of thin slab centerline segregation, eliminate thin slab centerline segregation is to further improve the quality of key pipeline technical problems.
3) Plate Unit: The main production of heavy plate for LSAW pipe production, reliable straight seam submerged arc welded pipe, widely used in high-voltage transmission and gas trunk line.
4) Steckel: Steckel mill comprises a reciprocating roughing mill and a finishing mill 4 roll back and forth. In the finishing mill both sides of the conveyor line installed two hot roll mill. Output roller typically comprises a laminar cooling system and a take-up station. On the Steckel mill, thermo-mechanical history of the entire length of the strip on the significant changes, especially in the micro-alloyed steel production, will strongly influence the degree of recrystallization generated in the finishing mill, grain growth and precipitation, and cause the entire dramatic changes in the final microstructure and mechanical properties of the strip length. Which process is characterized by relatively low investment costs.
In the domestic pipeline steel production process are: a conventional semi-continuous hot rolling, CSP continuous casting and rolling, plate units, Steckel unit.
1) Semi-continuous rolling mill: Includes 1 rack 5 rack Steckel mill and finishing mill. In the semi-continuous rolling mills, strip the finish rolling experienced hot-rolled steel strip from one end to the other end is substantially constant. On finishing mill time between passes is generally less than 3s.
2) CSP continuous casting and rolling: in CSP production line containing niobium, vanadium, titanium composite micro-alloyed carbon steel, the use of appropriate controlled rolling and cooling and coiling process can ensure the mechanical properties and microstructure of steel modern organizations meet the technical requirements of X60 pipeline steel, pipeline steel in line with modern trends. Our CSP continuous casting and rolling production line has been developed to X60 steel, while the United States and other foreign manufacturers CSP has developed and produced high-grade pipeline steel X60, X65 and the X70. Which process is characterized by the presence of thin slab centerline segregation, eliminate thin slab centerline segregation is to further improve the quality of key pipeline technical problems.
3) Plate Unit: The main production of heavy plate for LSAW pipe production, reliable straight seam submerged arc welded pipe, widely used in high-voltage transmission and gas trunk line.
4) Steckel: Steckel mill comprises a reciprocating roughing mill and a finishing mill 4 roll back and forth. In the finishing mill both sides of the conveyor line installed two hot roll mill. Output roller typically comprises a laminar cooling system and a take-up station. On the Steckel mill, thermo-mechanical history of the entire length of the strip on the significant changes, especially in the micro-alloyed steel production, will strongly influence the degree of recrystallization generated in the finishing mill, grain growth and precipitation, and cause the entire dramatic changes in the final microstructure and mechanical properties of the strip length. Which process is characterized by relatively low investment costs.
Characteristics of Pipe Cold Rolling
After a series of cold-rolled pipe has the following characteristics:
1, Through the organization of cold rolled grain fine pipe, pipe mechanical and physical properties compared with the superior;
2, Cold rolling mill for the correction capability of the original tube wall thickness deviation is large, precise geometry, low surface roughness;
3, Pass deformation larger, up to 70% -85%;
4, Cold-rolled production pipe can significantly reduce intermediate steps, such as heat treatment, pickling, beginning, straightening and cutting, to reduce the metal materials, fuel, electricity and other auxiliary materials and human consumption;
5, The method to produce cold-rolled thin wall and ultra-thin wall, inner and outer surfaces scratch-free quality pipe;
6, Be effectively rolled high-alloy, poor ductility various metal pipe.
1, Through the organization of cold rolled grain fine pipe, pipe mechanical and physical properties compared with the superior;
2, Cold rolling mill for the correction capability of the original tube wall thickness deviation is large, precise geometry, low surface roughness;
3, Pass deformation larger, up to 70% -85%;
4, Cold-rolled production pipe can significantly reduce intermediate steps, such as heat treatment, pickling, beginning, straightening and cutting, to reduce the metal materials, fuel, electricity and other auxiliary materials and human consumption;
5, The method to produce cold-rolled thin wall and ultra-thin wall, inner and outer surfaces scratch-free quality pipe;
6, Be effectively rolled high-alloy, poor ductility various metal pipe.
2016年9月19日星期一
Seamless Pipe Rolling
The raw material is rolled seamless steel pipe, tube embryos to go through a cutting machine cutting a length of about 1 meter blank, and by conveyor belt to the furnace heating. The billet is fed into the furnace is heated to a temperature of about 1200 degrees Celsius. The fuel is hydrogen or acetylene. Furnace temperature control is the key issue. After a round tube came out to go through the pressure punching machine wear air. Generally more common punch is tapered roller punching machine, punching machine such high production efficiency, product quality, perforated expanding capacity, can be worn a variety of steels. After perforation, round tube has been three-roll rolling, rolling or extrusion. To post extrusion detached sizing. Sizing high-speed rotary cone drill bit through the perforated steel embryo formed steel. Pipe inner diameter is determined by the outer diameter sizing mill drill length.
Pipe by sizing after entering the cooling tower through spray cooling pipe after cooling, will be straightening. After straightening the steel conveyor belt to the metal detection machine (or pressure test) for internal testing. If the thick-walled seamless internal cracks, bubbles and other issues, will be detected. After the selection of steel but also through strict quality control manual. After the steel quality inspection, using spray paint on number, size, production batch number. By a crane into the warehouse.
Pipe by sizing after entering the cooling tower through spray cooling pipe after cooling, will be straightening. After straightening the steel conveyor belt to the metal detection machine (or pressure test) for internal testing. If the thick-walled seamless internal cracks, bubbles and other issues, will be detected. After the selection of steel but also through strict quality control manual. After the steel quality inspection, using spray paint on number, size, production batch number. By a crane into the warehouse.
Cooling Ways of Seamless Steel Billet
According to the chemical composition of the seamless steel pipe, a state organization, product section size, deficiencies that may arise after cooling, and the rolling mill, cooling equipment, space and cooling conditions after hot rolling of steel can be used with different cooling methods to cool to room temperature.
1) Air-cooled
This is the natural air cooling method, it is applied very widely. After all the air is cooled, it is not a martensitic microstructure or steel, the use of air cooling after hot rolling, such as low carbon steel, low-alloy ordinary strength steel, most of the carbon steel and alloy semi-martensitic structure steel, and austenitic stainless steel, and are using this method of cooling.
2) Rapid cooling
It is blowing, spraying, water is forced through the cooling method of steel making process is characterized by a certain period drama cooled to a temperature in the cooled natural. Such as requiring testing carbide steel mesh defects using this cooling method. Carbon steel wire rod also rapid cooling after rolling, in order to improve the overall mechanical properties of the wire.
3) Slow cooling
It features after hot rolling steel slab or stack together to make it slowly cooled, to prevent white spot defects. The specific method of slow cooling according to the production conditions, and can be dedicated slow cooling pit, can be moved in a special slow cooling box to be stacked on the floor, cover with sand, slag and other asbestos insulation was subjected slow cooling. This cold
But approach applies to martensite, martensite and half Ledeburite type of steel, such as high speed tool steel, stainless steel, tool steel and high-alloy section high alloy structure, they produce stress upon cooling very sensitive strong.
4) Heat treatment
After the heat treatment method commonly used hot-rolled annealing, tempering, normalizing.
1) Air-cooled
This is the natural air cooling method, it is applied very widely. After all the air is cooled, it is not a martensitic microstructure or steel, the use of air cooling after hot rolling, such as low carbon steel, low-alloy ordinary strength steel, most of the carbon steel and alloy semi-martensitic structure steel, and austenitic stainless steel, and are using this method of cooling.
2) Rapid cooling
It is blowing, spraying, water is forced through the cooling method of steel making process is characterized by a certain period drama cooled to a temperature in the cooled natural. Such as requiring testing carbide steel mesh defects using this cooling method. Carbon steel wire rod also rapid cooling after rolling, in order to improve the overall mechanical properties of the wire.
3) Slow cooling
It features after hot rolling steel slab or stack together to make it slowly cooled, to prevent white spot defects. The specific method of slow cooling according to the production conditions, and can be dedicated slow cooling pit, can be moved in a special slow cooling box to be stacked on the floor, cover with sand, slag and other asbestos insulation was subjected slow cooling. This cold
But approach applies to martensite, martensite and half Ledeburite type of steel, such as high speed tool steel, stainless steel, tool steel and high-alloy section high alloy structure, they produce stress upon cooling very sensitive strong.
4) Heat treatment
After the heat treatment method commonly used hot-rolled annealing, tempering, normalizing.
2016年9月18日星期日
Welding Process of Straight Seam Welded Pipe
Longitudinal straight seam welded pipe butt weld joint cross-sectional shape, depending on the thickness of the body to be welded before welding groove and then type two sides. When welding thick steel plate, for penetration in contact at the edges out of various shapes of the groove, so that more easily into the welding rod or wire. Groove patterns are one-sided welding the welding groove and the sides of the groove. When you select groove type, in addition to outside should be considered to ensure penetration welding convenient, less filler metal Chi, small welding deformation and beveling of Longitudinal low cost factor.
Linker connecting the two is in the welding Longitudinal seam formed called weld. Both sides of the weld in the welding welding heat effect will be, but the organization and performance vary, this area is known as the heat affected zone. Welding due to the workpiece material welding materials, Longitudinal welding current so different, after welding may occur in the weld and heat affected zone of overheating, embrittlement, hardening or softening, but also the weldment performance degradation, deterioration of weldability. This need to adjust the welding conditions, before welding weldment interface preheating, post-weld heat when and weld heat treatment can improve the quality of welding weldment quality.
Longitudinal is of two or more homogeneous or heterogeneous material through a combination of diffusion and the question of the atom or molecule is integrally connected to the process, prompting the question of atoms and molecules produce binding and diffusion method is to heat or pressure, or simultaneously heated and pressurized.
In addition, a local weld foot rapid heating and cooling process, the weld zone due to the binding body and four weeks of the workpiece can not freely expand and contract in the weldment after cooling will produce welding stress and deformation. Important product after welding is required to eliminate welding stress, welding distortion correction
Linker connecting the two is in the welding Longitudinal seam formed called weld. Both sides of the weld in the welding welding heat effect will be, but the organization and performance vary, this area is known as the heat affected zone. Welding due to the workpiece material welding materials, Longitudinal welding current so different, after welding may occur in the weld and heat affected zone of overheating, embrittlement, hardening or softening, but also the weldment performance degradation, deterioration of weldability. This need to adjust the welding conditions, before welding weldment interface preheating, post-weld heat when and weld heat treatment can improve the quality of welding weldment quality.
Longitudinal is of two or more homogeneous or heterogeneous material through a combination of diffusion and the question of the atom or molecule is integrally connected to the process, prompting the question of atoms and molecules produce binding and diffusion method is to heat or pressure, or simultaneously heated and pressurized.
In addition, a local weld foot rapid heating and cooling process, the weld zone due to the binding body and four weeks of the workpiece can not freely expand and contract in the weldment after cooling will produce welding stress and deformation. Important product after welding is required to eliminate welding stress, welding distortion correction
How To Deal With The Welding Slag of Spiral Welded Pipe
Spiral welded pipe in recent years, the development of better and better in our lives are often used spiral welded pipe, spiral welded pipe in the welding process but will be some welding slag, which slag require extra care in handling only the spiral welded pipe more smoothly in the next use.
When the spiral welded pipe welding slag welding If welding is best to use, such as stainless steel pipe or cold after hammering, will fall off, these two methods are relatively simple, but not necessarily clean clean. Welding slag is better to clean up bad slag splashing is clear, when welding slag can clean up the electricity, then grind on electricity grinding, welding slag, otherwise it is difficult to be cleaned out. As for the defect occurs when spiral welded pipe cutting is also possible to get rid of us, however, to remove these defects must find a reasonable way only correct way to make pipe defects be remedied. For all these defects can find the appropriate solution, but if you find the right method will allow the use of more trouble. For when cleaning pipe welding slag there is a way you can with a file, with a file can also be cleaned very clean welding slag. There is a simpler way is to take the effort or a saw blade with a half can, out into the pipe, tube left hand, right hand saw blade, clockwise or counterclockwise to the arms pull. This allows spiral welded pipe in the welding slag clean very clean, but also will not waste too much time, simple and convenient.
When the spiral welded pipe welding slag welding If welding is best to use, such as stainless steel pipe or cold after hammering, will fall off, these two methods are relatively simple, but not necessarily clean clean. Welding slag is better to clean up bad slag splashing is clear, when welding slag can clean up the electricity, then grind on electricity grinding, welding slag, otherwise it is difficult to be cleaned out. As for the defect occurs when spiral welded pipe cutting is also possible to get rid of us, however, to remove these defects must find a reasonable way only correct way to make pipe defects be remedied. For all these defects can find the appropriate solution, but if you find the right method will allow the use of more trouble. For when cleaning pipe welding slag there is a way you can with a file, with a file can also be cleaned very clean welding slag. There is a simpler way is to take the effort or a saw blade with a half can, out into the pipe, tube left hand, right hand saw blade, clockwise or counterclockwise to the arms pull. This allows spiral welded pipe in the welding slag clean very clean, but also will not waste too much time, simple and convenient.
2016年9月10日星期六
Automatic Submerged Arc Welding Advantages of Straight Seam Steel Pipe
Submerged arc welding of straight seam steel pipe has the following advantages:
Submerged arc welding heat concentrated, welding safety metal spatter loss, there is no waste of the electrode head, workpiece thickness h may also be without groove, thus saving metal material.
Submerged arc welding can be employed large welding current, arc heat concentration, deep penetration, the wire can be continuously fed unlike electrodes as frequently replaced, so the productivity of 5 to 10 times higher than that of manual arc welding village.
Submerged arc welding is not visible arc welding, welding fumes and rarely, but also mechanical automatic operation, and thus the working conditions have been greatly improved. Submerged arc welding is a limitation: since the arc is not visible, thus demanding joint processing and assembly, welding position subject to certain restrictions, are generally always in flat-position welding.
Submerged arc welding heat concentrated, welding safety metal spatter loss, there is no waste of the electrode head, workpiece thickness h may also be without groove, thus saving metal material.
Submerged arc welding can be employed large welding current, arc heat concentration, deep penetration, the wire can be continuously fed unlike electrodes as frequently replaced, so the productivity of 5 to 10 times higher than that of manual arc welding village.
Submerged arc welding is not visible arc welding, welding fumes and rarely, but also mechanical automatic operation, and thus the working conditions have been greatly improved. Submerged arc welding is a limitation: since the arc is not visible, thus demanding joint processing and assembly, welding position subject to certain restrictions, are generally always in flat-position welding.
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