The heat treatment performed after welding to improve the microstructure and performance of the welded joint or eliminate the residual stress of welding is called post-weld heat treatment. The functions of post-weld heat treatment of welded joints are:

(1) Reduce residual stress.

(2) Adjust the mechanical properties of welded joints.

(3) Improve the metallographic structure of the heat-affected zone of the weld metal.

The functions of post-weld stress relief heat treatment are as follows:

(1) Reduce or eliminate the residual welding stress caused by welding.

(z) Reduce the hardness of the heat affected zone.

(3) Reduce the diffusible hydrogen content in the weld.

(4) Improve the plasticity of welded joints.

(5) Improve the impact toughness and fracture toughness of welded joints.

(6) Improve resistance to stress corrosion.

(7) Improve organizational stability.