The use of seamless steel tubes is very good, and we can see seamless steel pipes in many places. The seamless steel pipe has a good effect. However, it has some very complicated processes during the processing.
In the process of seamless steel pipe, there are many steps to obtain a pipe with such high quality. By eliminating the work hardening of the seamless steel pipe, a satisfactory metallographic structure can be obtained. The process equipment is a bright annealing furnace, which is mainly used for the stainless steel product is heat treated under a protective atmosphere.
When the application performance requirements of seamless steel tubes are different, the requirements for the metallographic structure after bright annealing are different, so the process of bright heat treatment will be different. After cold working, residual stress is left in the seamless steel pipe material, and the residual stress is very unfavorable to the stress corrosion cracking of the pipe. Any degree of cold working will result in a significant increase in the resistance to stress corrosion cracking of the material.
The degree of cold working also has an adverse effect on the high temperature endurance of austenitic stainless steel. The higher the general working temperature or the higher the fracture life requirement, the lower the degree of cold working.
Improving the use of seamless steel pipe
From the above introduction, it can be known that the heat treatment process of the seamless steel pipe is rather cumbersome, and in order to obtain a qualified metallographic structure, the adjustment section of the cooling section of the bright annealing furnace is required to be large. Therefore, the current advanced bright annealing furnaces often use strong convection cooling in their cooling sections, and three cooling sections are provided, which can individually adjust the air volume. It is divided into three sections along the width direction of the strip, and the cooling rate in the width direction of the strip is adjusted by the air flow guiding to control the plate shape.
Uniformity of the strip
Another important problem in the heat treatment of cold-rolled strip steel for seamless steel tubes is that the entire strip is required to be evenly distributed in width and length. The muffle-type bright annealing furnace uses a large-sized muffle tube to uniformly wind the heating airflow from the outside of the muffle tube to evenly heat the strip. To ensure uniformity of the strip along the length of the length of the strip, it is necessary to maintain the linear speed of the stainless steel strip in the furnace.
Therefore, the roller tension adjusting device can be precisely adjusted before and after the current advanced vertical heat treatment furnace. It not only needs to make the strip import and export speed meet the requirements of heat treatment speed, and is not affected by the empty sleeve or full sleeve of the live sleeve. It is also necessary to establish and precisely adjust the small tension of the strip according to the plate shape of the strip to meet the stainless steel plate type requirements.