Metal Heat Treatment

The metal heat treatment is to heat the metal or alloy workpiece to a suitable temperature in a certain medium, and after maintaining the temperature for a certain period of time, it is cooled in different media at different speeds, by changing the surface or interior of the metal material. A process of microstructural structure to control its performance. cnc machining part

Main category
Metal heat treatment processes can be roughly divided into three categories: overall heat treatment, surface heat treatment and chemical heat treatment. Depending on the heating medium, heating temperature and cooling method, each category can be divided into several different heat treatment processes. The same metal uses different heat treatment processes to obtain different microstructures and thus different properties. Steel is the most widely used metal in the industry, and the steel microstructure is also the most complex, so there are many kinds of steel heat treatment processes. brass cnc machining part

Characteristics
Metal heat treatment is one of the important processes in mechanical manufacturing. Compared with other processing methods, heat treatment generally does not change the shape and overall chemical composition of the workpiece, but changes the microstructure inside the workpiece or changes the chemical composition of the surface of the workpiece. , to give or improve the performance of the workpiece. It is characterized by improved intrinsic quality of the workpiece, which is generally not visible to the naked eye. Therefore, it is a special process in mechanical manufacturing and an important part of quality management.

In order to make the metal workpiece have the required mechanical properties, physical properties and chemical properties, in addition to the rational selection of materials and various forming processes, heat treatment processes are often essential. 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 the like can also be modified by heat treatment to obtain different mechanical properties, physical properties, and chemical properties.

Basic process

The overall heat treatment is a metal heat treatment process that heats the workpiece as a whole and then cools it at an appropriate speed to change its overall mechanical properties. The overall heat treatment of steel has four basic processes: annealing, normalizing, quenching and tempering. plastic part

Annealing is to heat the workpiece to a suitable temperature, using different holding times according to the material and the size of the workpiece, and then slowly cooling, in order to bring the internal structure of the metal to or near equilibrium, or to release the internal stress generated by the previous process. Get good process performance and performance, or prepare for further quenching.

Normalizing or normalizing is to cool the workpiece to a suitable temperature and then cool it in air. The effect of normalizing is similar to annealing, but the resulting structure is finer, which is often used to improve the cutting performance of materials, and sometimes used for some requirements. The parts that are not high are used as the final heat treatment.

Quenching is to rapidly cool the workpiece after heating and holding it in a quenching medium such as water, oil or other inorganic salt solution or organic aqueous solution. After quenching, the steel becomes hard but becomes brittle at the same time.

In order to reduce the brittleness of the steel, the quenched steel is insulated for a long time at a suitable temperature above room temperature and below 650 ° C, and then cooled. This process is called tempering. Annealing, normalizing, quenching and tempering are the "four fires" in the overall heat treatment. Among them, the quenching and tempering are closely related, and often used together, they are indispensable.