The normalizing process is used to make the steel structure finer, homogenize the carbides, and eliminate residual stress, making the steel easier to cut. Since hardenability is also improved, normalizing is sometimes used as a pretreatment process before quenching.

Poor quenching or tempering can lead to problems such as insufficient hardness, cracks, deformation, and damage to molds and fixtures. Processed products such as mechanical parts, machine tools and functional components may break or bend after being assembled into the machine, which may cause user complaints and claims.

Quenching and tempering under appropriate heat treatment conditions according to the specific steel type are essential to ensure the quality required for its application.

The general heat treatment process of steel is as follows:

Steel type selection

Processing→Inspection→Cleaning→Quenching→Cleaning (if oil quenching)→Tempering→Post-treatment (as needed)

Inspection

Because the metal is heated to a high temperature during the heat treatment process, the metal combines with moisture and oxygen in the air to form oxides, which is called oxidation. In subsequent processes, these oxides need to be removed by grinding or other methods. Decarburization may also occur when the steel is heated. The carbon in the surface layer combines with oxygen in the air, resulting in carbon reduction.