Heat treatment is a kind of metal thermal processing technology that controls the performance of a metal material by heating, keeping warm, and cooling it in a certain medium by changing the metallographic structure on the surface or inside of the material.

Heat treatment process features

Metal heat treatment is one of the important processes in mechanical manufacturing. Compared with other processing technologies, heat treatment generally does not change the shape of the workpiece and the overall chemical composition. Instead, it changes the microstructure inside the workpiece or changes the chemical composition of the workpiece surface. , Give or improve the performance of the workpiece. Its characteristic is to improve the inherent quality of the workpiece, which is generally not visible to the naked eye.

In order to make the metal workpieces have the required mechanical properties, physical properties and chemical properties, in addition to the rational selection of materials and various forming processes, the heat treatment process is often indispensable. Steel is the most widely used material in the machinery industry. The microstructure of steel is complex and can be controlled by heat treatment. Therefore, the heat treatment of steel is the main content of metal heat treatment. In addition, aluminum, copper, magnesium, titanium, and their alloys can also be changed by heat treatment of their mechanical, physical and chemical properties to obtain different performance.

Classification of heat treatment process

The metal heat treatment process can be roughly divided into three categories: overall heat treatment, surface heat treatment and chemical heat treatment. According to the different heating medium, heating temperature and cooling method, each major category can be divided into several different heat treatment processes. Different heat treatment processes are used for the same metal to obtain different structures and thus have different properties. Steel is the most widely used metal in the industry, and the microstructure of the steel is also the most complex. Therefore, there are many kinds of steel heat treatment processes.

The overall heat treatment is a metal heat treatment process in which the entire workpiece is heated and then cooled at an appropriate rate to obtain the desired metallographic structure to change its overall mechanical properties. The overall heat treatment of steel generally has four basic processes of annealing, normalizing, quenching and tempering.