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...