To avoid residual stresses after welding, alloy steels:

The primary goal of preheating and post-weld heat treatment in alloy steels is to minimize residual stresses and reduce the risk of thermal cracking during the welding process. When welding, the intense heat can cause rapid thermal expansion and contraction of the welded materials, leading to distortion and residual stresses that may compromise the structural integrity of the component.

Heating the alloy steels before welding helps achieve a more uniform temperature distribution, reducing the heat differential between the weld area and the surrounding material. This approach limits the rapid cooling that can result from welding, which can otherwise generate significant stresses. During the welding process, maintaining appropriate temperatures can help ensure that the weld is integrated smoothly into the base material, further reducing stress concentrations.

After welding, the post-weld heat treatment allows the material to relieve some of the stresses that may have developed during the process. This can help to temper the material, improving ductility and toughness while reducing residual stresses. Therefore, heating the alloy steels before, during, and after welding is essential to effectively control residual stresses and improve the overall performance and safety of the welded structure.