What is the purpose of post-weld heat treatment?

The purpose of post-weld heat treatment is primarily to relieve residual stresses that may have developed during the welding process and to improve the mechanical properties of the weld. When metals are heated and cooled during welding, they can experience uneven thermal expansion and contraction. This can lead to internal stresses within the material, which can compromise its structural integrity and performance.

By applying a controlled heat treatment after welding, these residual stresses can be reduced, leading to a more uniform distribution of stress throughout the welded joint. Additionally, post-weld heat treatment can enhance the toughness, ductility, and overall mechanical performance of the weld, making it more suitable for its intended application.

Choices related to improving aesthetic appearance, cleaning the weld surface, or cooling the weld area do not address the crucial role of heat treatment in stress relief and mechanical enhancement, which is essential for ensuring the long-term reliability and safety of welded structures.