The process of changing the internal structure of metal parts through certain heating, heat preservation and cooling processes (or at the same time changing the chemical composition of the surface layer) to obtain the required performance is called heat treatment.
Many machine parts and engineering components are subject to various heat treatments. The main purposes are:
1) Make the workpiece obtain good craftsmanship, so that various processing can be carried out smoothly.
2) Give the workpiece the mechanical properties (or physical or chemical properties) required by the design to make it work normally, increase the service life, reduce costs, and obtain good economic effects.