steel tube

　　The reason for the corrosion of the stainless steel seamless pipe was analyzed except for the atmosphere inside, the oxide tube of the oxide film of all metals in the oxygen. Unfortunately, the iron oxide formed in the oxidation of the ordinary metal tube continues, and the rust will continue to expand, eventually forming pores. You should paint or oxidize metals (eg zinc, nickel and chrome) to ensure carbon steel surfaces. 　　But because people know that this protection is just a movie. If the protective layer is destroyed, these simple steel plates begin to rust. Stainless steel seamless tubes will depend on chromium corrosion resistance, but because chromium is an element of steel to ensure that source protection is not the same. 　　The integrated chromium level reached 10.5%, the annealed tube, the atmospheric corrosion resistant steel increased significantly, but the chromium content was higher, but still improved corrosion resistance, but not obvious. Due to the processing of...

　　Cold crack, one of most important steps for ERW steel pipe producing, plays an essential role for quality of welded steel pipe. Then how to control the technical steps to decrease the shortage of cold crack? 　　There are two main aspects for this: the role of hydrogen and quenching effect. 　　The role of hydrogen: Temperature control would be important for welding steel pipe production process. Some of the hydrogen atoms are in the compound of the state of the precipitation of hydrogen resolution, and large amount of hydrogen will be dissolved in the metal bath. As the bath temperature dropped, the solubility of hydrogen in the metal drastically reduced. However, quickly cooling of the weld pool, the hydrogen too late to escape and remains in the weld metal. 　　Quenching effect: Near the weld seam zone or cold cracks formed on the metal phase transition process and the mechanical properties of rapidly changing and complex stress state. Cold cracking occurs mainly in medium carbon...

　　We’ve introduced three types of cold crack for ERW steel pipe simply. For more understanding of it, we will list them for details. Thus, we will know how to decide once we need to purchase them. 　　Three types of cold cracks are boundary cracks, under-bead cracks and root cracks. 　　Boundary cracks: This type is from weld and base metal junction began to extend the base material. 　　Under-bead cracks: In the weld seam below the near area, it is not developed to the base metal surface. 　　Root cracks: Cracks form originated in the root of the weld notch stress concentration at the heat affected zone, which extends into the base metal or welds. 　　With more discussion, welcome your email us：marketing@xysteelpipe.com.

　　Talking about seamless steel pipe , we cannot ignore the discussion about stress relief annealing of it. And our main topic today would be the temperature for the producing of the steel pipe. So discussing here if you have any troubles for steel pipe. 　　Temperature of process of stress relief annealing would be category as followed list: 　　First of all, the workpiece was slowly heated to Ac 1 or less 100 ~ 200 ℃ (500 ~ 600 ℃); 　　Then, holding a certain time (1 ~ 3h) followed by slow furnace cooling to 200 ℃, baked and then cooled. 　　And for steel, it is generally 500 ~ 600 ℃,Iron is generally 500 ~ 550 ℃ likely to cause pearlite graphitization than 550. 　　Finally, weldment generally 500 ~ 600 ℃.

　　There is visible sign for seamless steel pipe and welded one even you are just a fresh for those steel pipes. You would call it seamless one once you see there is no crack in the surface. Here is the question: why we adopt the perforation process for seamless steel pipe? 　　The first concern is, of course, its function. As we all know, seamless steel pipe would be the best partner for transmitting the high pressure medium. They can be oil, gas, and water. And the main purpose for the perforation process is here. First of all, it would make a solid round billet piercing hollow shell. And seamless steel pipe, produced by perforation process, would meet the requirement of accuracy, surface quality, specifications and so on. What’s more, once the steel pipe transports the dangerous products, they are not just produced for safety, but for lots of aspects’ reasons.

　　The term seamless steel pipe is believed to be familiar to many people. It is not well understood that it is only a detailed classification. Because the types and types of steel pipes are numerous and numerous, the number of pipes including plastics has reached tens of thousands in the world. These pipes are used in various ways, and every pipe from the sewer to the city plays a role. The most important role, the process development, makes thick-walled steel pipes, which are smaller than 20 diameter, into hot-selling pipes. 　　Many people may be unfamiliar, but they use this material in many channels. For example, buildings such as some other industries use seamless steel pipes because the walls of thick-walled seamless steel pipes are thick and durable. Widely used. Thick-walled steel pipes can also be used as sewage pipes. It can also be used as oil pipes. Nowadays, the underground passages of the city are indispensable for thick-walled steel pipes. Steel pipes are also used to b...

　　The seamless steel tubes are mostly medium-sized, high-carbon alloy steels. After quenching, some of the supercooled austenite is not transformed into martensite, and remains in the used state to become retained austenite, which affects the performance. If it is cooled below zero, it can promote the martensite transformation of the retained austenite. Therefore, the essence of the cold treatment is that the quenching continues. The quenching stress at room temperature is superimposed on the quenching stress at zero, and the cold treatment crack is formed when the refolding stress exceeds the strength limit of the material. 　 　Precautionary measures: 　　(1) The seamless steel pipe is placed in boiling water for 30-60 minutes before quenching after quenching, which can eliminate 15%-25% quenching internal stress and stabilize retained austenite, then -60 °C Conventional cold treatment, or cryogenic treatment at -120 ° C, the lower the temperature, the more the retained austenite tr...

　　Galvanized seamless pipes are divided into hot-dip galvanizing and cold-galvanizing. The hot-dip galvanized steel tube is obtained by reacting a molten metal with an iron matrix to produce an alloy layer, thereby combining the substrate and the plating layer. Hot-dip galvanizing is to pickle the steel pipe first, in order to remove the iron oxide on the surface of the steel pipe, after pickling, it is washed by ammonium chloride or zinc chloride aqueous solution or a mixed aqueous solution of ammonium chloride and zinc chloride, and then fed. 　　Hot dip plating tank. Hot-dip galvanizing has the advantages of uniform plating, strong adhesion and long service life. The steel pipe matrix and the molten plating solution undergo complex physical and chemical reactions to form a corrosion-resistant structure of a zinc-iron alloy layer. The alloy layer is integrated with the pure zinc layer and the steel pipe base. Therefore, its corrosion resistance is strong. 　　1. Uniformity of galvani...

　　Small-diameter thick-walled seamless pipes are steel pipes with a small ratio of outer diameter to wall thickness. How should such steel pipes be heat treated? 　　1. The repaired parts need to be normalized during the heat treatment process. The normalizing is a heat treatment process of heating the small-diameter thick-walled tubes of seamless steel tubes to 45 ° C above Ac3, and after cooling for a suitable time, in a static air. Structural parts requiring mechanical properties require quenching after normalizing to meet mechanical performance requirements. Medium and high alloy steels and large forgings require high temperature tempering after normalizing to eliminate the internal stress generated during normalizing. 　　2. Annealing treatment of small-diameter thick-walled tubes of seamless steel tubes is a heat treatment process in which metals and alloys are heated to a suitable temperature for a certain period of time and then slowly cooled. After annealing, the sub-eutectoi...

　　Features of precision seamless steel pipe : 　　1. High precision, saving the loss when machining the user's materials. 　　2. There are many specifications and a wide range of applications. 　　3. The cold rolled product has high precision, good surface quality and good straightness. 　　4. The inner diameter of the steel pipe can be made into a hexagon. 　　5. The performance of the steel pipe is superior and the metal is relatively dense. 　　Advantages of precision seamless steel pipe: 　　Compared with solid steel such as round steel, seamless steel pipe has a light weight when it has the same bending and torsional strength. It is an economical section steel and is widely used in the manufacture of structural parts and mechanical parts. Precision steel pipes also have their own characteristics while inheriting the advantages of seamless steel pipes. Precision manufacturing of ring parts can improve material utilization, simplify manufacturing processes, save materials and pr...

　　Austempering is one of the effective quenching methods for reducing the deformation and cracking of seamed steel pipes (straight seam steel pipes , spiral steel pipes and erw steel pipes ) and seamless steel pipe, but how to properly use the process should be based on the material, size, hardness and toughness of the steel pipe. The requirements for deformation, as well as the specific working conditions, etc., are reasonably selected. The following issues to be noted for the isothermal quenching of seamless steel tubes are summarized below for reference by heat treatment operators. 　　[1] For austempering of steels with low hardenability such as carbon seamless steel tubes, the quenching heating temperature should be appropriately increased, the stability of austenite should be increased, and the high temperature non-Bayesian in the isothermal process should be avoided and prevented. The transformation of the body. 　　[2] Austempering is limited by the size of steel and steel. In ...

　 　1. Capillary tube 　　The wall thickness of the capillary tube should be uniform, and the surface defects on the inner and outer surfaces should be small; the outer surface polishing and inner hole defect cleaning equipment should be arranged. 　　 2. Reexamination 　　Compared with ordinary cold drawn steel pipe, cold drawn precision seamless steel pipe production increases the hot-rolled capillary pickling re-inspection process, mainly to ensure that there are no defects such as folding and crack on the outer surface of the capillary tube, and the inner surface is excluded from folding and severely scribed. Tubes with defects such as pockmarks. 　 　3. Tools 　　Generally, the surface smoothness of tools used in the production of cold-drawn precision seamless steel tubes is above Ra0.4, the dimensional accuracy is above H3, and the hardness is required to be above HRC70. At the same time, it is required that the tip or mold sticking phenomenon cannot occur during the drawing proc...

　　We’ve got that stainless steel pipe has its drawbacks when applied in different environment. So here is the question for our customers: How to choose appropriate grade stainless steel pipe to prolong its service life? 　　Finding the suitable grade steel pipeline would be an important lesson. There are some basic examples for customers: 　　Basic ferritic grades would be necessary. Taking chromium-alloyed steel tube for example, EN grade steel pipeline has a corrosion resistance that is usually adequate for interior applications. Thus, you can wholesale relative steel pipes here for your engineering project. 　　For chromium-nickel grade, it would have similar situation. 　　Whether cholorides or sulphur dioxides are to be expected in the atmosphere, thus, choosing the appropriate grade steel tube would be an important lesson for our customers. 　　 http://www.xysteelpipe.com/info/How-to-choose-the-right-grade-of-stainless-steel-pipe-1289-1.htm

　　During the heating and cooling process of the cold drawn seamless steel pipe , due to the inconsistency between the cooling rate and the time of the surface layer and the core, a temperature difference is formed, which causes volume expansion and uneven shrinkage to generate stress, that is, thermal stress. Under the action of thermal stress, since the surface layer starts to be lower than the core, the contraction is also larger than the core and the core is pulled. 　　When the cooling is finished, the core is compressed due to the final cooling volume shrinkage of the core pulled. That is, under the action of thermal stress, the surface of the workpiece is finally pressed and the core is pulled. This is now affected by factors such as cooling rate, material composition and heat treatment process. 　　The faster the cooling rate, the higher the carbon content and the cold-drawn seamless steel pipe material composition, the greater the uneven plastic deformation caused by thermal st...

　　In urban construction, the role of seamless steel pipes is also very large. This kind of pipeline material is used as a transportation pipeline for groundwater in urban construction, and it is often buried deep. In today's cities, many places The sewers are being rebuilt. The pipe materials used are seamless steel pipes. The seamless steel pipes are corrosion resistant. Therefore, they are very good choices as pipe materials. The groundwater is dirty and corrosive, and seamless steel pipes are used. Transportation can be a good solution to this problem. 　　Seamless steel pipes can not only be used to transport groundwater, but also energy transportation is also very convenient. It is also a good choice for transportation and natural gas. It is transported with seamless steel pipes and is not prone to leakage. In the case of safety, the seamless steel pipe has a distinct advantage compared with the spiral pipe. Therefore, the advantage is still obvious. This pipe material has be...

　　 Spiral pipe has the following advantages: 　　(1) Steel pipes of the same width can be used to produce steel pipes of different diameters. In particular, large diameter steel pipes can be produced from bismuth strip steel. 　　(2) The stress of the spiral weld is smaller than that of the straight seam, which is only 75-90% of the straight welded pipe, so it can bear a large pressure. 　　(3) The size is accurate. Generally, the diameter tolerance is less than 0.12%, the deflection is less than 1/2000, and the ellipticity is less than 1%. Generally, the sizing and straightening process can be omitted. 　　(4) Continuous production: In theory, it is possible to produce steel pipes without infinite length, with small loss of cutting head and tail cutting, which can improve the utilization factor of metal by 6~8%. 　　(5) Flexible operation, easy to change the variety (compared with straight seam welded pipe). 　　(6) The equipment is light in weight, with low initial investment, and s...

　　The factors affecting the welding quality of high-frequency welded pipes mainly include the following aspects: 　　 (1) Welding pressure 　　It is one of the main parameters of the welding process and affects the strength and toughness of the weld. If the welding pressure is too small, the welded edges cannot be sufficiently pressed, so that the strength of the weld is lowered, and the force is easily cracked once the force is applied. If the welding pressure is too large, the strength of the weld will be lowered, and defects such as burrs and lap welding are likely to occur. 　　If we want to control the welding pressure, we can do this by adjusting the spacing of the squeezing rollers. 　　 (2) Welding speed 　　It is also one of the main parameters of the welding process, mainly related to heating temperature, weld deformation speed and crystallization speed. In general, the welding speed is fast, the welding quality is good, but the maximum speed allowed, can not exceed this val...

　　Domestic high-precision seamless steel pipes generally improve the properties of materials by adding alloys to metals. After cold drawing, seamless steel pipes need to be subjected to stress relief annealing to eliminate residual stress of materials, improve material structure and improve materials. Plasticity, so as to prevent the occurrence of fracture failure of seamless steel pipe. 　　At present, the material of China's stainless steel seamless steel pipe is ordinary 45# or 20# steel 27SiMn steel, which improves the strength of the metal by cold drawing deformation; however, it is at the expense of plasticity and toughness of the sacrificial metal. High-precision cold-drawn seamless steel pipe is based on its high dimensional accuracy and high strength performance. It must ensure that the deformation amount is within a certain range to maximize the performance of the material and reduce the material. Negative Effects. 　　The deformation of the seamless steel pipe is too sm...

　　When the hydraulic test of the erw steel pipe is carried out, it is often found that the bursting opening is cracked from the weld of the erw steel pipe, which indicates that the strength of the welded portion is lower than that of the base metal. Through experimental analysis, it is found that if an internal scraping groove is formed on the inner surface of the steel pipe during the removal of the burr in the weld, the wall thickness of the sample at the weld bead is reduced, and the sample is easily broken from the tensile test. 　　The water pressure test of the water supply pipeline is the means for the final quality assessment of the erw steel pipe laying. Generally, there are two main requirements for the hydraulic pressure test: one is that it can correctly reflect the leakage of the pipeline; the other is the pressure test. No problem, nor can the interface be damaged due to pressure test, but it will affect the quality of the project, or retry the work, resulting in waste, ...

　　1. Comparison of wall thickness tolerance between erw steel pipe and seamless steel pipe 　　ERW steel pipe: hot-rolled coil is used as raw material, the thickness limit of modern hot-joining can be controlled within 0.05mm, and the seamless steel pipe is produced by round steel perforation, the wall thickness deviation is large, and the subsequent hot rolling can partially eliminate the wall. Thickness unevenness, but the current advanced unit can only be controlled within ±5~10%t, corresponding to the thickness of 8.94mm steel pipe. 　　Seamless steel pipe: The limit of wall thickness control accuracy is 0.9mm. 　　2. ERW steel pipe and seamless steel pipe compared with outer diameter tolerance 　　ERW steel pipe: adopts cold-bending forming, and the sizing is completed by 0.6% reduction. The process temperature is basically constant at room temperature, so the outer diameter control is accurate and the fluctuation range is small, which is good for eliminating black leather buckle...