Longitudinal use from the nearest point of view, using hydroformed tubes used in auto parts concern. Using the hydroforming process systems due to complexity, large pressure, therefore possible to improve the workability of steel. However, previous evaluations steel workability indicators are not clear, I hope to develop a simple evaluation processing technology.
As the hydraulic tube forming equipment is huge, high prices, so the compact hydraulic forming equipment in high demand by the automobile manufacturers and steel plants work together to develop a new concept of compact hydraulic forming equipment. For the production of thick-walled welded pipe, some manufacturers have developed resistance welding and laser welding and high frequency welding combined with technology. In the past, laser welding for the production of stainless steel, will be applied to the welded steel pipe forming speed production lines forming the first time. This technology is due to the development of high power laser generating device before achieved. From a manufacturing technical point of view, the stability of the thick-walled pipe and weld portion forming process technology as key to the development, of low deformation tube technology developed in Japan CBR technique which can produce high-strength steel good processability.
Tuesday, November 19, 2013
SAW straight seam steel coil manufacturing technology
In general, the coil volume header, the volume at the end of the board edge straightness easily exceeded, and prone to heavy skin folds, scars, indentations, scratches and other imperfections and defects, and thus cut steel Kaiping, the appearance and geometric dimensions conform to the technical requirements of the plate lower pass rate, calculated based on the volume weight and the actual weight per unit length of the coil, the budget out of steel rolls long, the whole rationale for determining the shear length and number of sheets of qualified steel; same time as the on-site inspection volume Kaiping head and capuchin defects in real time straight from the severe degree of excessive volumes and closing coil be cut; straightness exceeded for larger volume header plates and capuchin plate edge milling to increase the amount.
Due to the volume board without slitting, rolling board edge defects and imperfections easily exist, such as heavy paper, folded, scarring, indentations, scratches, etc., which feed on the road when the first steel reinforced manual inspection. In addition, because billet steel hot rolled into plates immediately after a coil winding, coiling temperature of 500-600 degrees Celsius, and therefore can not be in the steel mills UT hierarchical testing, coil quality can not be guaranteed. So steel technical conditions "are subject to 100% of all steel stratified testing for 100% of the scan." Domestic steel plant in the feeding line are equipped ultrasonic flaw detection process layering, layering plates thus conducted online testing can be achieved, but the scan area, generally scan area can reach 25 % or more. To improve the scanning coverage of the probe of the packet is changed to a slow walk straight swing back and forth scan, the scan area can be increased to 40 % or more, to ensure the quality of the inner plate line.
Collage volume level edge milling and forming, welding and outside the pre- welding, weld and weld edges enhance elimination board edge defect inspection is the best way. X-ray tube weld industrial TV or X-ray film examination to strengthen the seam side edges 20-50mm base material inspection, pipe automatic weld seam edges UT flaw detection increases stratified parent material testing and inspection, can be very ensure good quality steel pipe weld edge.
Due to the volume board without slitting, rolling board edge defects and imperfections easily exist, such as heavy paper, folded, scarring, indentations, scratches, etc., which feed on the road when the first steel reinforced manual inspection. In addition, because billet steel hot rolled into plates immediately after a coil winding, coiling temperature of 500-600 degrees Celsius, and therefore can not be in the steel mills UT hierarchical testing, coil quality can not be guaranteed. So steel technical conditions "are subject to 100% of all steel stratified testing for 100% of the scan." Domestic steel plant in the feeding line are equipped ultrasonic flaw detection process layering, layering plates thus conducted online testing can be achieved, but the scan area, generally scan area can reach 25 % or more. To improve the scanning coverage of the probe of the packet is changed to a slow walk straight swing back and forth scan, the scan area can be increased to 40 % or more, to ensure the quality of the inner plate line.
Collage volume level edge milling and forming, welding and outside the pre- welding, weld and weld edges enhance elimination board edge defect inspection is the best way. X-ray tube weld industrial TV or X-ray film examination to strengthen the seam side edges 20-50mm base material inspection, pipe automatic weld seam edges UT flaw detection increases stratified parent material testing and inspection, can be very ensure good quality steel pipe weld edge.
Straight seam welded steel pipe heat treatment
Straight seam steel pipe weld heat treatment is a new technique to eliminate residual stress. Preheated before welding the material to a heat treatment temperature after the welding process and welding pieces of heating was continued to maintain this temperature, the soldering is completed using heat insulation cotton to its slow cooling. This method can effectively reduce residual stress and improve the stress corrosion resistance of metals.
NDT weld inside the pipe in the water supply as part of large steel works, especially the thickness t=30mm steel tube is used as a pipe bridge, both to withstand the water pressure, but also the burden of weight and water from the pipe forming moment, so the welding quality requirements are particularly high. For pipe bridge of t=30mm thick with a large-diameter steel pipe, the longitudinal seam and girth welds belong to a class, require 100% of X-ray film examination and 100 % of the ultrasonic flaw detection; while the thickness t=24mm buried pipe, belongs to a class of longitudinal seam welding, for 20 % of the X-ray film examination and 50 % of the ultrasonic flaw inspection.
Heat treatment after welding can reduce the residual stress, and heat treatment temperature is higher, the better to eliminate the residual stress. Large diameter steel pipe weld heat treatment can effectively improve the large-diameter steel pipe stress corrosion resistance, heat treatment temperature is higher, increasing resistance to stress corrosion is more significant. Diffusion of metal carbide coating technology is the workpiece on special media, the diffusion layer is formed on the surface of several microns to several tens of micrometers of the metal carbide layer. Large diameter steel pipe anti-corrosion of buried pipes and tubes inside out corrosion, are used to hang galvanized wire, spraying compressive strength of not less than 30N/mm2 cement mortar lining.
NDT weld inside the pipe in the water supply as part of large steel works, especially the thickness t=30mm steel tube is used as a pipe bridge, both to withstand the water pressure, but also the burden of weight and water from the pipe forming moment, so the welding quality requirements are particularly high. For pipe bridge of t=30mm thick with a large-diameter steel pipe, the longitudinal seam and girth welds belong to a class, require 100% of X-ray film examination and 100 % of the ultrasonic flaw detection; while the thickness t=24mm buried pipe, belongs to a class of longitudinal seam welding, for 20 % of the X-ray film examination and 50 % of the ultrasonic flaw inspection.
Heat treatment after welding can reduce the residual stress, and heat treatment temperature is higher, the better to eliminate the residual stress. Large diameter steel pipe weld heat treatment can effectively improve the large-diameter steel pipe stress corrosion resistance, heat treatment temperature is higher, increasing resistance to stress corrosion is more significant. Diffusion of metal carbide coating technology is the workpiece on special media, the diffusion layer is formed on the surface of several microns to several tens of micrometers of the metal carbide layer. Large diameter steel pipe anti-corrosion of buried pipes and tubes inside out corrosion, are used to hang galvanized wire, spraying compressive strength of not less than 30N/mm2 cement mortar lining.
Tuesday, November 12, 2013
Longitudinal and spiral welded differences and blasting methods
The main difference of longitudinal and spiral welded pipe lies in the two different production processes, the formation of the first Longitudinal molding machine through the first hot rolled coil shape, so that it becomes smooth cylindrical outer surface, and then soldering, welding or the use of a solder layer of the proximity effect of arcing and burning of the skin effect, the edge of the heating tube and melted in a suitable cooled compression molding. LSAW and ERW tube edge is melted in different ways by the distinction, generally called by arc melting LSAW steel pipe and ERW is the use of high-frequency current melted. Spiral welded pipe production process is to follow the appropriate helix angle of the low-carbon low-alloy structural steel and carbon steel coils into the tube, and then seam welded pipe forming. Spiral welded pipe spiral submerged arc welded pipe is the main form. Can narrow the billet production of large diameter spiral steel pipe is the most significant feature is widely used in all walks of life of the gas pipeline construction.
To reduce the quality of the coating, layer type and construction of environmental factors on the life of the coating Longitudinal should be regularly Longitudinal rust. There are four common rust, namely, pickling, cleaning, descaling and tools rust spray. Pickling is the most common ways of rust, sand-blasting not only can be used as a further treatment step after, but also the Longitudinal surface rust, scale, old coatings completely removed, although this cleaning method make steel surface roughness and cleanliness requirements are up to par, but that is a chemical cleaning method, likely to cause pollution of the surrounding environment. Straight seam steel pipes cleaned only as an adjunct to anti-corrosion treatment, because the steel surface cleaning methods can only dust, grease and lubricants and other residual organics removed, and can not play antiseptic effect, as we usually wash Like, you can clean the surface of the dirt, most bacteria are still left in the hand. Professional and technical personnel with a wire brush and other cleaning tools on the surface to be polished, this approach is known tools rust, loose rust, welding slag and oxide so can be completely removed, but for steel surface firmly attached oxide is powerless and can not achieve the standard preservative effect. Jet is the use of grit blasting, steel shot abrasive materials such as high-quality powerful centrifugal force through the jet to jet straight seam steel surface, not only can effectively remove surface dirt, rust and oxides, etc., will be as abrasive roughness Longitudinal friction and achieve the standard required under the action.
To reduce the quality of the coating, layer type and construction of environmental factors on the life of the coating Longitudinal should be regularly Longitudinal rust. There are four common rust, namely, pickling, cleaning, descaling and tools rust spray. Pickling is the most common ways of rust, sand-blasting not only can be used as a further treatment step after, but also the Longitudinal surface rust, scale, old coatings completely removed, although this cleaning method make steel surface roughness and cleanliness requirements are up to par, but that is a chemical cleaning method, likely to cause pollution of the surrounding environment. Straight seam steel pipes cleaned only as an adjunct to anti-corrosion treatment, because the steel surface cleaning methods can only dust, grease and lubricants and other residual organics removed, and can not play antiseptic effect, as we usually wash Like, you can clean the surface of the dirt, most bacteria are still left in the hand. Professional and technical personnel with a wire brush and other cleaning tools on the surface to be polished, this approach is known tools rust, loose rust, welding slag and oxide so can be completely removed, but for steel surface firmly attached oxide is powerless and can not achieve the standard preservative effect. Jet is the use of grit blasting, steel shot abrasive materials such as high-quality powerful centrifugal force through the jet to jet straight seam steel surface, not only can effectively remove surface dirt, rust and oxides, etc., will be as abrasive roughness Longitudinal friction and achieve the standard required under the action.
The choice of straight seam submerged arc welding steel pipe
(1) required for the high peak pipeline, because the user's gas consumption is very uneven, frequent fluctuations in the pipeline pressure, alternating steel to withstand the stress is large, defects will already in pipes alternating stress expansion if optional multi- weld defect high probability spiral welded steel pipe, pipeline safety operations will not be guaranteed.
(2) Pipeline crossing earthquake fault or through local high intensity earthquake zone, because these lots geologically active, which will have a vertical or axial pipe alternating stress. Spiral weld is much higher chance than LSAW steel pipe, in the long term stress, spiral welded steel pipe is much higher than the chance of an accident LSAW steel pipe, therefore, in this zone should be used straight submerged arc welded pipe.
(3) internal and external coating demanding pipes, LSAW steel pipes should be used. Multi- spiral submerged arc welded pipe weld, the weld reinforcement generally higher than LSAW high on steel pipe inside and outside corrosion, the corrosion-resistant materials combined with the bare pipe LSAW degree as closely antiseptic effect is not good LSAW steel pipes.
(4) For critical wear crossing project, you should use LSAW steel pipe. Since future maintenance and management difficulties than the general line segment, therefore, with excellent performance LSAW particularly necessary.
(5) For piping weak links, such as hot simmer elbow pipe, LSAW steel pipe should be used. Hot simmer elbow as change of direction, which is subject to external forces than the general lines of straight pipe should be large, because the simmer process affected by various factors, the stress is not easy to eliminate long-distance pipeline is weak link using an integrated LSAW good performance can make up for these deficiencies.
(2) Pipeline crossing earthquake fault or through local high intensity earthquake zone, because these lots geologically active, which will have a vertical or axial pipe alternating stress. Spiral weld is much higher chance than LSAW steel pipe, in the long term stress, spiral welded steel pipe is much higher than the chance of an accident LSAW steel pipe, therefore, in this zone should be used straight submerged arc welded pipe.
(3) internal and external coating demanding pipes, LSAW steel pipes should be used. Multi- spiral submerged arc welded pipe weld, the weld reinforcement generally higher than LSAW high on steel pipe inside and outside corrosion, the corrosion-resistant materials combined with the bare pipe LSAW degree as closely antiseptic effect is not good LSAW steel pipes.
(4) For critical wear crossing project, you should use LSAW steel pipe. Since future maintenance and management difficulties than the general line segment, therefore, with excellent performance LSAW particularly necessary.
(5) For piping weak links, such as hot simmer elbow pipe, LSAW steel pipe should be used. Hot simmer elbow as change of direction, which is subject to external forces than the general lines of straight pipe should be large, because the simmer process affected by various factors, the stress is not easy to eliminate long-distance pipeline is weak link using an integrated LSAW good performance can make up for these deficiencies.
Monday, November 4, 2013
Precision light pipe welding temperature
Precision bright tubes solid tube inspection and removal of surface defects, cut into desired length, end to end in the perforated tube surface-centering, and then sent to the furnace heating, punch a hole. In the hole while continuing to rotate and move forward in the roll and the role of the head, gradually formed within the tube cavity, called the capillary. And then sent to the automatic rolling machine to continue rolling. Finally after all the whole entire wall thickness are, after sizing mill sizing, to specifications. Use of continuous pipe mill producing hot-rolled precision light pipe is a more advanced methods. If you wish to get smaller and better quality seamless, must be rolled, drawn or a combination of methods. Cold is usually performed on two-roll mill, pipe hole in the variable section tapered slot and does not move the head of the circular hole formed in the rolling. Drawing is usually 0.5 ~ 100T single chain or double chain drawing machine on. Heating tube extrusion method is about good squeeze on the closed cylinder, perforated extruded rod rod and move together, so that extrusion from the smaller hole in the extrusion die. This method can produce smaller diameter of the pipe. After coating the coating material on the precision light pipe ri pretreatment indirectly affect the quality of the coating off the power attached to compete.
Titanium solid solution strengthening effect is strong, but the toughness of reducing solid solution, solid solution in austenite to improve the hardenability of steel, but titanium compounds , but lower hardenability of steel. Improve the tempering stability, and a secondary hardening effect in enhancing the oxidation resistance and heat resistant steel heat resistance, such as creep and rupture strength, and improve the weldability of steel. Precision light pipe welding temperature is mainly affected by the impact of high-frequency eddy current heating power, high-frequency eddy current frequency heating power is mainly affected by the impact of thermal power and eddy current excitation frequency is proportional to the square; while current excitation frequency but also by the excitation voltage, current, and capacitance, inductance. Use of this technology and the production of hot-rolled steel welded pipe common essential difference between the high-frequency furnace heating the weld through the parent microstructure and mechanical properties can be achieved entirely consistent Additionally, multiple passes through the tension -reducing rolling machines and automatic control makes precision light pipe size accuracy (especially tube roundness and wall thickness accuracy) than similar. Produced in the developed world, fluid pipes, boiler tubes have been widely used pipe seamless process, with the development of society, domestic hot-rolled precision light pipe welded to gradually replace the situation has been formed.
Titanium solid solution strengthening effect is strong, but the toughness of reducing solid solution, solid solution in austenite to improve the hardenability of steel, but titanium compounds , but lower hardenability of steel. Improve the tempering stability, and a secondary hardening effect in enhancing the oxidation resistance and heat resistant steel heat resistance, such as creep and rupture strength, and improve the weldability of steel. Precision light pipe welding temperature is mainly affected by the impact of high-frequency eddy current heating power, high-frequency eddy current frequency heating power is mainly affected by the impact of thermal power and eddy current excitation frequency is proportional to the square; while current excitation frequency but also by the excitation voltage, current, and capacitance, inductance. Use of this technology and the production of hot-rolled steel welded pipe common essential difference between the high-frequency furnace heating the weld through the parent microstructure and mechanical properties can be achieved entirely consistent Additionally, multiple passes through the tension -reducing rolling machines and automatic control makes precision light pipe size accuracy (especially tube roundness and wall thickness accuracy) than similar. Produced in the developed world, fluid pipes, boiler tubes have been widely used pipe seamless process, with the development of society, domestic hot-rolled precision light pipe welded to gradually replace the situation has been formed.
Precision light pipe fundamental properties of liquid metals
Density of atoms in the liquid light pipe as heat energy is still larger, higher precision light control its intensity in three dimensions each atom adjacent atoms are often collide with each other, replacing energy. In the collision, some energy to the atoms in the other a fragmentary atoms, and their energy declined. Precision light pipe is all the time there are some consequences of atomic energy even beyond atomic energy, some of the energy of atomic energy is much smaller than the uniform. Precision light pipe heterogeneity of this energy is called energy fluctuation. Energy fluctuation exist in liquid form within the group each atom has a larger atomic kinetic energy near the atomic overcome the constraints (joint formed between atoms barrier), in addition to strong heat occurring within the group still (vacancy occurs and dispersion) in addition, precision light pipe also in clusters from the original groups were added to other atomic groups or form new atomic groups. Thus, precision light pipe despite everything ferrite grain atomic groups are in a rapidly changing situation, sometimes grow and sometimes smaller, sometimes occurs and sometimes disappear, one after another, as in swimming without pause.
This structure is called rapidly changing structure and downs. Precision light pipe above three characteristics of the liquid metal choices based features: a fixed volume , precision light pipe has good mobility, a variety of physical and chemical properties close to the solid state, and away from the gaseous state. Precision bright tubes present, at home and abroad on the nature of the liquid metal to make a small amount of research, here only u stagnation of liquid metal, basic physical appearance and sense of nature scenes. Study the chemical composition of metal species indicated, individual state comparable metal different than the coefficient of friction of the contact metal to be large; each other can cause friction between the alloying metal, can not be compared with each other alloys or compounds caused to a large coefficient of friction. Precision light pipe without smooth conditions, some pure metal contact practice coefficient of friction. However, in practice, the course of the rolling appearance much smaller than the coefficient of friction between the net coefficient of friction between the metal surface. Precision light pipe because of the nature and status of seizures practice appearance change, so changes to the friction conditions episodes, such as the change from the adhesive friction sliding friction, the friction coefficient will lead to landing.
This structure is called rapidly changing structure and downs. Precision light pipe above three characteristics of the liquid metal choices based features: a fixed volume , precision light pipe has good mobility, a variety of physical and chemical properties close to the solid state, and away from the gaseous state. Precision bright tubes present, at home and abroad on the nature of the liquid metal to make a small amount of research, here only u stagnation of liquid metal, basic physical appearance and sense of nature scenes. Study the chemical composition of metal species indicated, individual state comparable metal different than the coefficient of friction of the contact metal to be large; each other can cause friction between the alloying metal, can not be compared with each other alloys or compounds caused to a large coefficient of friction. Precision light pipe without smooth conditions, some pure metal contact practice coefficient of friction. However, in practice, the course of the rolling appearance much smaller than the coefficient of friction between the net coefficient of friction between the metal surface. Precision light pipe because of the nature and status of seizures practice appearance change, so changes to the friction conditions episodes, such as the change from the adhesive friction sliding friction, the friction coefficient will lead to landing.
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