Steel is the most widely used material in the mechanical industry. Its microstructure is complex and can be controlled through heat treatment. Therefore, heat treatment of steel is the main content of metal heat treatment. In addition, aluminum, copper, magnesium, titanium, and their alloys can also be heat treated to change their mechanical, physical, and chemical properties to achieve different performance.

Heat treatment refers to a metal heat processing process in which materials are heated, insulated, and cooled in a solid state to obtain the desired structure and properties. In the process of advancing from the Stone Age to the Bronze Age and the Iron Age, the role of heat treatment has gradually been recognized.