Post-weld heat treatment of 13CrMo44 steel

At present, the application of low-alloy heat-resistant steels in the petrochemical industry is becoming more and more common, especially Cr-Mo type heat-resistant steels. Because this type of steel contains a certain amount of carbon and alloy elements, it has a certain hardening tendency during welding. Under the action of large restraint stress, it is easy to produce cold cracks and poor weldability. Therefore, preheating must be carried out before welding, and post-weld heat treatment must be carried out in order to accelerate the escape of diffusible hydrogen after welding.

The post-weld heat treatment of 13CrMo44 steel is divided into two types: overall heat treatment and local heat treatment. In the pipeline installation, the post-weld heat treatment generally adopts local heat treatment, that is, the heat treatment method of wrapping the weld seam with an electric heating belt to heat, and wrapping the insulation layer outside for heat preservation.

Post-weld heat treatment can not only eliminate the welding residual stress generated in the welding process of 13CrMo44 steel, but also can improve the structure of base metal, improve the comprehensive mechanical properties of 13CrMo44 steel joints, and also improve the high temperature creep strength and the stability of its structure can reduce the hardness of 13CrMo44 steel weld and heat-affected zone.

From the above analysis, it can be seen that when 13CrMo44 steel is used for pipeline installation, it is very important to formulate a reasonable heat treatment process. It can ensure that 13CrMo44 steel does not produce cracks and delayed cracks during welding, which is a prerequisite for improving project quality.