Thick wall seamless carbon steel pipe

Detail treatment of thick-walled seamless carbon steel pipe processing

In the processing of thick-walled seamless steel pipes, many steps are required to obtain such high-quality pipes. By eliminating the work hardening of the seamless pipe, a satisfactory metallographic structure can be obtained. The process equipment is bright annealing furnace, which is mainly used for. The finished stainless steel is heat treated in a protective atmosphere. When the application performance requirements of the thick-walled seamless steel pipe are different, the requirements for the metallographic structure after bright annealing are also different, so the bright heat treatment process will also be different.

The residual stress of the thick-walled seamless steel pipe material remains after cold working, and the residual stress is very unfavorable to the stress corrosion cracking of the pipeline. Any degree of cold working can significantly improve a material's resistance to stress corrosion cracking. The degree of cold working can also adversely affect the high temperature resistance of austenitic stainless steels. Generally speaking, the higher the working temperature or the higher the fracture life requirement, the lower the degree of cold working.

It can be seen from the above introduction that the heat treatment process of thick-walled seamless steel pipes is quite troublesome. In order to obtain a qualified metallographic structure, the adjustment part of the cooling section equipment of the bright annealing furnace needs to be very large. Therefore, the current advanced bright annealing furnace usually adopts strong convection cooling in its cooling section, and has three cooling sections, and the air volume can be adjusted independently. It is divided into three sections along the width of the strip.

According to the production method, thick-walled seamless steel pipes can be divided into three categories: hot rolling (extrusion), welding and cold working. Hot-rolled seamless steel pipe is a steel pipe in which a solid billet or ingot is pierced and rolled into a hollow section. The basic process is piercing and rolling. Cold-worked seamless steel pipe is the secondary processing of steel pipe (also includes the secondary processing of thick-walled seamless steel pipe and thin-walled seamless steel pipe). Cold working is an important method to obtain high-precision, high-performance pipes, including cold rolling, cold drawing, cold drawing and cold spinning, etc. Extruded non-ferrous metal seamless pipes for high alloy steel grades are mainly extruded.

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