There are many processes in the processing of welded steel pipes, and we need to pay attention to every detail. You can learn about the heat treatment of welded steel pipes in the process of welded steel pipes.

Welded steel pipes need to go through various processes before they are used. The heat treatment of welded steel pipes is a very important link in the processing of welded steel pipes. Thermal processing is a metal thermal processing process in which metal materials are heated, kept warm, and cooled in a certain medium, and the metallographic structure of the material surface or interior is changed to control its metal properties. During the heating and cooling process of the structural welded steel pipe workpiece, due to the inconsistency of the cooling rate and time between the surface layer and the core, a temperature difference is formed, which will lead to uneven volume expansion and contraction and stress, that is, thermal stress.

Under the action of thermal stress, since the surface temperature is lower than that of the core, the contraction is greater than that of the core and the core is pulled. When the cooling is over, the core is compressed because the final cooling volume of the core cannot shrink freely By pull. That is, under the action of thermal stress, the surface of the workpiece is finally compressed and the core is pulled. This phenomenon is affected by factors such as cooling rate, material composition, and heat treatment process. When the cooling rate is faster, the carbon content and alloy composition are higher, the uneven plastic deformation produced under the action of thermal stress during the cooling process is greater, and the final residual stress is greater. On the other hand, during the heat treatment process of steel, due to the change of the structure, that is, when the austenite transforms into martensite, the increase of the specific volume will be accompanied by the expansion of the volume of the workpiece, and the phase transformation of each part of the workpiece will cause the volume to grow inconsistently and produce microstructure. stress. The final result of tissue stress changes is that the surface is subjected to tensile stress and the core is subjected to compressive stress, which is just the opposite of thermal stress. The size of the structural stress is related to the cooling rate, shape, chemical composition of the material, and other factors of the workpiece in the martensitic transformation zone.

In order to make welded steel pipe workpieces have the required mechanical properties, physical properties, and chemical properties, in addition to a reasonable selection of materials and forming processes, heat treatment processes are often essential. Steel is a widely used material in the machinery industry. The microstructure of steel is complex and can be controlled by heat treatment. Therefore, the heat treatment of steel is the main content of metal heat treatment. In addition, aluminum, copper, magnesium, titanium, etc., and their alloys can also change their mechanical, physical, and chemical properties through heat treatment to obtain different performances.