Why is normalizing performed after welding?

Normalizing is a heat treatment process applied after welding primarily to relieve internal stresses that develop in the base metal due to the heating and cooling cycles associated with the welding process. When metal is welded, it experiences rapid temperature changes that can create uneven distribution of stress within the material. These residual stresses can lead to warping, cracking, or other forms of structural failure if not addressed.

By normalizing, the metal is heated to a specific temperature and then allowed to cool in air, which helps to equalize the structure of the material, refine the grain size, and improve the mechanical properties of the metal. This process aids in restoring ductility and toughness, making the metal less susceptible to failure during subsequent use.

While the appearance of the weld may improve following normalizing and certain types of heat treatments can influence brittleness, the primary purpose of the normalizing process is focused on stress relief. Ensuring uniform thickness is generally more associated with welding techniques and processes rather than a consequence of normalizing.