Surface microcracks of lsaw steel pipe impact on product quality greatly, ranging from commuted, while in retirement, especially niobium, vanadium, titanium Longitudinal most prominent, has seriously affected the improvement of product quality and finished product rate. This not only gives the enterprise has brought huge economic losses, but also restricts the development of varieties of plate production line. Longitudinal surface microcracks mainly has edge crack, longitudinal, star cracks, its causes both improper rolling process parameter control, there are abnormal production of continuous casting process, the slab cracks genetic, residual element enrichment.
Longitudinal surface microcracks severely affect product quality. Longitudinal surface micro cracks main reason is the continuous casting mold copper coating off. This aspect will lead to copper penetration into the solidified shell austenite grain boundaries, grain boundary cracks; on the other hand will be uneven due to thermal stress cracks and crack sensitivity containing titanium steel strong performance is particularly evident . Control measures: To improve the quality of mold copper, copper to prevent dew; strengthen inspection before production of slab quality and production after Longitudinal; Longitudinal protection through good casting and other measures to improve Longitudinal steel cleanliness.
2019年10月15日星期二
Prewelding process of LSAW steel tube
LSAW steel pipes (UOE, JCOE) manufacturing processes, welding processes are set to continuous advance. Its role is to be finalized after the tube forming, shaping and positioning within the weld seam on the back cover, in order to ensure the pipe dimensions and is conducive to tube welded pipe to improve quality and production efficiency.
Pre-welding process
After forming the tube by the next roller conveyor transported to a pre-welder's torch, rising rotating roll, rotate to adjust an open position to weld at the top of both sides of the pressure on the pressure roller and the pressure roller so that the tube seam, drop gun and adjust the tracking of the weld seam, open the protective gas and cooling water, start welding, welding condition monitoring, welded to the tube end welding arc stops (automatic delay stop gas), lift the gun and the top pressure rollers, pipe welder pre sent , pipe ends and welding defects.
Pre-welding process characteristics
Pre-welding using Ar + CO2 mixed gas shielded arc welding, continuous welding seam on the back of the tube to move at a faster speed. Since the bevel angle, tube shape, the tube along the longitudinal direction of the opening and both sides of the plate edge distortion factors of inequality, forming the seam after seam quality is not stable, larger changes. Need to change the tube seam welding, the arc of a steady state, the weld position deviated from the case and other real-time tracking and adjusted accordingly. Thus presoldered have welding speed, impact seam quality factors, changes and adjustments randomness and other characteristics.
Pre-welding process
After forming the tube by the next roller conveyor transported to a pre-welder's torch, rising rotating roll, rotate to adjust an open position to weld at the top of both sides of the pressure on the pressure roller and the pressure roller so that the tube seam, drop gun and adjust the tracking of the weld seam, open the protective gas and cooling water, start welding, welding condition monitoring, welded to the tube end welding arc stops (automatic delay stop gas), lift the gun and the top pressure rollers, pipe welder pre sent , pipe ends and welding defects.
Pre-welding process characteristics
Pre-welding using Ar + CO2 mixed gas shielded arc welding, continuous welding seam on the back of the tube to move at a faster speed. Since the bevel angle, tube shape, the tube along the longitudinal direction of the opening and both sides of the plate edge distortion factors of inequality, forming the seam after seam quality is not stable, larger changes. Need to change the tube seam welding, the arc of a steady state, the weld position deviated from the case and other real-time tracking and adjusted accordingly. Thus presoldered have welding speed, impact seam quality factors, changes and adjustments randomness and other characteristics.
Application of High Pressure Boiler Tube In Life
The rapid development of the national economy has led to the improvement of people's living standards, which have contributed to the development of the power industry. The power industry is environmentally viable and in line with our sustainable development strategy. According to China's resources, China is still dominated by thermal power at this stage and for a long time to come.
It is said that the electric power industry should mention high-pressure boiler tubes. The boiler tubes are steels that are open at both ends and have a hollow section. The steel with a relatively large length and the surrounding area can be divided into seamless steel pipes and welded steel pipes according to the production method. Dimensions (such as outer diameter or side length) and wall thickness indicate a wide range of sizes, from small diameter capillaries to large diameter pipes up to several meters in diameter. Steel pipes can be used in pipelines, thermal equipment, machinery industry, petroleum geological exploration, containers, chemical industry and special applications. In general, the high-pressure boiler tube is also a kind of seamless steel pipe, and its production process is the same as that of the seamless steel pipe. However, high-pressure boiler tubes are important components of power station boilers, used to manufacture high-pressure and ultra-high-pressure power station boilers, and are used to build large-scale thermal power plants.
Therefore, high-pressure boiler tubes are often in a high-temperature, high-pressure environment, so the requirements for his raw material billets are required. It is very strict and requires high durability and high corrosion resistance, oxidation resistance, and good stability.This will require you to shop around when you choose a high-pressure boiler tube, compare the price, but also to compare the quality.
http://www.xysteelpipe.com/info/Application-of-High-Pressure-Boiler-Tube-In-Life-1528-1.htm
It is said that the electric power industry should mention high-pressure boiler tubes. The boiler tubes are steels that are open at both ends and have a hollow section. The steel with a relatively large length and the surrounding area can be divided into seamless steel pipes and welded steel pipes according to the production method. Dimensions (such as outer diameter or side length) and wall thickness indicate a wide range of sizes, from small diameter capillaries to large diameter pipes up to several meters in diameter. Steel pipes can be used in pipelines, thermal equipment, machinery industry, petroleum geological exploration, containers, chemical industry and special applications. In general, the high-pressure boiler tube is also a kind of seamless steel pipe, and its production process is the same as that of the seamless steel pipe. However, high-pressure boiler tubes are important components of power station boilers, used to manufacture high-pressure and ultra-high-pressure power station boilers, and are used to build large-scale thermal power plants.
Therefore, high-pressure boiler tubes are often in a high-temperature, high-pressure environment, so the requirements for his raw material billets are required. It is very strict and requires high durability and high corrosion resistance, oxidation resistance, and good stability.This will require you to shop around when you choose a high-pressure boiler tube, compare the price, but also to compare the quality.
http://www.xysteelpipe.com/info/Application-of-High-Pressure-Boiler-Tube-In-Life-1528-1.htm
2019年10月14日星期一
Various factors affecting the hardenability of steel
Due to the high hardenability and strengthening the role of alloying elements, some high strength martensitic stainless steel, high speed tool steel and high-strength alloy steel. Often in the quench (or tempering) after a high-temperature tempering, the steel carbide appropriate aggregation obtain coarse carbide particles tempered sorbite organization (with ball annealing similar organizations) Thus, this delivery steel state has good cutting performance cooling directly after delivery, known as hot rolling or forging state, after hot rolling or forging steel and not subject to special heat treatment. Hot rolling (forging) termination temperature is generally 800-900 ℃, after the general natural cooling in the air, and thus hot rolling (forging) state corresponds to normalizing. Unlike strict normalizing heating temperature control, the difference because of hot-rolled (forging) termination temperature high and low. Thus it is well done microstructure and properties of the steel shaken ratio.
1. That many steel companies controlled rolling, since the finishing temperature control is very strict and forced cooling after finish rolling to take measures so that grain refinement of steel, delivery of steel with high mechanical properties. Since the appearance of the skin is covered with a layer of iron oxide, which has a certain degree of corrosion resistance, as stringent storage requirements are not kept cold drawn (rolled) state delivery of steel, medium-sized steel, thick steel plate can be in the open air yard or through thatch cover and store the non-twist and controlled cooling hot rod location is the truth, hot-rolled (forging) state of delivery than ordinary steel hot rod performance.
2. Cold drawn (rolled) on steel hardenability without any heat treatment and direct delivery, the status of the cold drawing, cold-rolled steel cold forming. Called cold-drawn or cold-rolled condition. Cold-drawn steel dimensions (rolled) state of high accuracy, good surface quality, appearance roughness is low, and have high mechanical properties, compared with the hot rolling (forging) state. Since the cold drawn (rolled) state of delivery without scale steel outer cover, and there is a big stress, vulnerable to corrosion or rust, and thus cold drawn (rolled) state steel, packaging, storage and transportation are more stringent requirements, generally need to be in the custody of the Treasury, and the Treasury should pay attention to the temperature and humidity control the delivery state within the state, said normalizing. Since normalizing heating temperature (hypoeutectoid steel as Ac3 + 3050 ° C eutectoid steel as Accm + 3050 ° C than hot-end temperature control strict.
3. Before normalizing the status of the steel factory and normalizing heat treatment. Thus the structure of the steel, a uniform performance. Since normalizing cooling faster, compared to steel annealed state. Pearlite structure of the steel increased number of pearlite lamellar and grain refinement of steel, and thus have higher mechanical properties, and help to improve the low carbon steel widmanstatten and eutectoid steel cementite net, for further heat treatment of the finished product do organizational readiness.
1. That many steel companies controlled rolling, since the finishing temperature control is very strict and forced cooling after finish rolling to take measures so that grain refinement of steel, delivery of steel with high mechanical properties. Since the appearance of the skin is covered with a layer of iron oxide, which has a certain degree of corrosion resistance, as stringent storage requirements are not kept cold drawn (rolled) state delivery of steel, medium-sized steel, thick steel plate can be in the open air yard or through thatch cover and store the non-twist and controlled cooling hot rod location is the truth, hot-rolled (forging) state of delivery than ordinary steel hot rod performance.
2. Cold drawn (rolled) on steel hardenability without any heat treatment and direct delivery, the status of the cold drawing, cold-rolled steel cold forming. Called cold-drawn or cold-rolled condition. Cold-drawn steel dimensions (rolled) state of high accuracy, good surface quality, appearance roughness is low, and have high mechanical properties, compared with the hot rolling (forging) state. Since the cold drawn (rolled) state of delivery without scale steel outer cover, and there is a big stress, vulnerable to corrosion or rust, and thus cold drawn (rolled) state steel, packaging, storage and transportation are more stringent requirements, generally need to be in the custody of the Treasury, and the Treasury should pay attention to the temperature and humidity control the delivery state within the state, said normalizing. Since normalizing heating temperature (hypoeutectoid steel as Ac3 + 3050 ° C eutectoid steel as Accm + 3050 ° C than hot-end temperature control strict.
3. Before normalizing the status of the steel factory and normalizing heat treatment. Thus the structure of the steel, a uniform performance. Since normalizing cooling faster, compared to steel annealed state. Pearlite structure of the steel increased number of pearlite lamellar and grain refinement of steel, and thus have higher mechanical properties, and help to improve the low carbon steel widmanstatten and eutectoid steel cementite net, for further heat treatment of the finished product do organizational readiness.
Low carbon steel welding process
Low carbon steel has a carbon content of ≤0.25%, and its plasticity is good. Generally, it has no tendency to harden, is not sensitive to the welding process, and has good weldability. When welding such steels, special process measures are not required, and heat treatment (except electroslag welding) is usually not required after welding.
For low-carbon steel structures with a thickness greater than 50 mm, high-current multi-layer welding is commonly used, and internal stress annealing is eliminated after welding. When the structure with high welding rigidity in a low temperature environment is large, the temperature difference between the parts of the weldment is large, and the deformation is limited. The welding process is prone to generate large internal stress, which may cause cracking of the structure. Therefore, preheating before welding should be performed.
Low carbon steel can be welded by various welding methods, and the most widely used are electrode arc welding, submerged arc welding, electroslag welding, gas shielded welding and electric resistance welding.
When welding structural steel by fusion welding, the selection of welding materials and processes should mainly ensure the strength of welded joints and workpiece materials. Welding rod arc welding is generally low carbon steel structure, E4313 (J421), E4303 (J422), E4320 (J424) welding rod can be selected. When welding dynamic load structures and complex structures, E4316 (J426), E4315 (J427) or E5015 (J507) electrodes should be used. For submerged arc welding, H08A or H08MnA welding wire with flux 431 is generally used for welding.
For low-carbon steel structures with a thickness greater than 50 mm, high-current multi-layer welding is commonly used, and internal stress annealing is eliminated after welding. When the structure with high welding rigidity in a low temperature environment is large, the temperature difference between the parts of the weldment is large, and the deformation is limited. The welding process is prone to generate large internal stress, which may cause cracking of the structure. Therefore, preheating before welding should be performed.
Low carbon steel can be welded by various welding methods, and the most widely used are electrode arc welding, submerged arc welding, electroslag welding, gas shielded welding and electric resistance welding.
When welding structural steel by fusion welding, the selection of welding materials and processes should mainly ensure the strength of welded joints and workpiece materials. Welding rod arc welding is generally low carbon steel structure, E4313 (J421), E4303 (J422), E4320 (J424) welding rod can be selected. When welding dynamic load structures and complex structures, E4316 (J426), E4315 (J427) or E5015 (J507) electrodes should be used. For submerged arc welding, H08A or H08MnA welding wire with flux 431 is generally used for welding.
2019年10月8日星期二
Anti-corrosion and heat preservation performance of spiral steel tube
Anti-corrosion insulation pipe with corrosion resistance of steel, and has good insulation properties, has been widely used and promoted in building construction, and constantly improve and spread. Corrosion pipe insulation having different processing types and methods, different processing method to determine the pipe have different properties and functions, and the use range also changes. As the name suggests, it is to increase the number of external spiral steel pipe corrosion insulation class protection, in order to achieve low temperature can be used. In general, the use of second degree pipe insulation inorganic zinc-rich paint, which temperature ≥400 ℃, belonging to corrosion coating, conduit port is used polyethylene film called 3-layer PE or using cold sealing tapes to achieve the previously installed to prevent moisture entering into the water or construction.
Spiral steel pipe insulation for high temperature, water and fuel pumps, chemical pump corrosive. Insulation pipeline centrifugal pump series products with low noise, performance, energy efficient and reliable. The insulation material used is a multi-layer bandaging wrong seam, so it is effective to reduce the heat loss, but also able to control the jacket surface measures to prevent the generation of cold bridges, so that the outer coating of temperature control is guaranteed. Spiral steel pipe wrapped with insulation material multilayer reflective layer of aluminum foil, which can effectively reduce the loss of heat, and can make the steam pipe can be more economical and reasonable. Anti-corrosion steel pipe insulation is a good corrosion resistance, along with good insulation properties, has been widely used and promoted in the design and construction, the current and constantly perfected and popularized. Spiral steel also have different types and methods of processing, while the different processing method to determine the pipe have different properties and functions, and range will change!
Spiral steel pipe insulation for high temperature, water and fuel pumps, chemical pump corrosive. Insulation pipeline centrifugal pump series products with low noise, performance, energy efficient and reliable. The insulation material used is a multi-layer bandaging wrong seam, so it is effective to reduce the heat loss, but also able to control the jacket surface measures to prevent the generation of cold bridges, so that the outer coating of temperature control is guaranteed. Spiral steel pipe wrapped with insulation material multilayer reflective layer of aluminum foil, which can effectively reduce the loss of heat, and can make the steam pipe can be more economical and reasonable. Anti-corrosion steel pipe insulation is a good corrosion resistance, along with good insulation properties, has been widely used and promoted in the design and construction, the current and constantly perfected and popularized. Spiral steel also have different types and methods of processing, while the different processing method to determine the pipe have different properties and functions, and range will change!
Method for Distinguishing the Quality of Seamless Steel Pipes
The use of seamless steel pipes is becoming wider and wider. When we choose seamless steel pipes, we must test the quality of seamless steel pipes. The following small series is detailed for everyone:
1. The fake and inferior seamless steel pipe is easy to be scratched, because the equipment of the fake and inferior seamless steel pipe manufacturers is simple, easy to produce burrs and scratch the surface of the steel. Deep scratches reduce the strength of the steel.
2. The counterfeit seamless steel pipe has no metallic luster and is light red or similar to pig iron.
3. The cross-fabricity of the counterfeit seamless steel pipe is thin and low, and the phenomenon of filling and dissatisfaction often occurs. The reason is that the manufacturer has to achieve a large negative tolerance, and the reduction of the first few passes of the finished product is too large, the iron type is small, and the hole type is not full.
4. The cross-section of the counterfeit semanufacturer has to reduce the amount of the two rolls in front of the finished roll in order to save material. The strength of this seamless steel pipe is greatly reduced, and it does not conform to the seamless steel pipe. The standard of the dimensions.
5. The composition of high-quality seamless steel pipe is uniform, the tonnage of the cold-shearing machine is high, the end face of the cutting head is smooth and tidy, and the surface of the inferior seamless steel pipe is often poor due to poor material, and the end face of the cutting head often has a phenomenon of falling meat, that is, unevenness, and no Metallic luster. And because the fake and inferior manufacturers have fewer heads, big ears will appear at the head and tail.
6. The fake and inferior seamless steel pipe material contains many impurities, the density of the steel is small, and the size is too bad, so in the absence of the vernier caliper, it can be weighed and checked. In general, the whole box weighing effect will be better, mainly considering the problem of cumulative error and probability theory.
http://www.xysteelpipe.com/info/Method-for-Distinguishing-the-Quality-of-Seamless-Steel-Pipes-1520-1.htm
1. The fake and inferior seamless steel pipe is easy to be scratched, because the equipment of the fake and inferior seamless steel pipe manufacturers is simple, easy to produce burrs and scratch the surface of the steel. Deep scratches reduce the strength of the steel.
2. The counterfeit seamless steel pipe has no metallic luster and is light red or similar to pig iron.
3. The cross-fabricity of the counterfeit seamless steel pipe is thin and low, and the phenomenon of filling and dissatisfaction often occurs. The reason is that the manufacturer has to achieve a large negative tolerance, and the reduction of the first few passes of the finished product is too large, the iron type is small, and the hole type is not full.
4. The cross-section of the counterfeit semanufacturer has to reduce the amount of the two rolls in front of the finished roll in order to save material. The strength of this seamless steel pipe is greatly reduced, and it does not conform to the seamless steel pipe. The standard of the dimensions.
5. The composition of high-quality seamless steel pipe is uniform, the tonnage of the cold-shearing machine is high, the end face of the cutting head is smooth and tidy, and the surface of the inferior seamless steel pipe is often poor due to poor material, and the end face of the cutting head often has a phenomenon of falling meat, that is, unevenness, and no Metallic luster. And because the fake and inferior manufacturers have fewer heads, big ears will appear at the head and tail.
6. The fake and inferior seamless steel pipe material contains many impurities, the density of the steel is small, and the size is too bad, so in the absence of the vernier caliper, it can be weighed and checked. In general, the whole box weighing effect will be better, mainly considering the problem of cumulative error and probability theory.
http://www.xysteelpipe.com/info/Method-for-Distinguishing-the-Quality-of-Seamless-Steel-Pipes-1520-1.htm
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