Heat treatment is a method of reheating, heat preservation or cooling of solid steel to change its structure to meet the requirements of the use of parts or process requirements. The height of heating temperature, the length of holding time, and the speed of cooling can cause different structural changes in steel. The blacksmith immerses the heated steel parts in water for rapid cooling (experts call it quenching) to increase the hardness of the steel parts. This is an example of heat treatment.
The heat treatment process includes annealing, normalizing, quenching and tempering. Annealing is to heat the steel parts for a certain period of time, and then slowly cool them together with the furnace to obtain a finer and uniform structure and reduce the hardness to facilitate cutting. Normalizing is to heat the steel parts, take them out of the furnace after heat preservation, and then cool them in the air, which is suitable for refining low carbon steel. Quenching is to heat the steel parts, and then quickly cool them in water or oil after heat preservation to increase the hardness. Tempering is usually the subsequent process of quenching. The quenched steel parts are reheated, kept warm and then cooled to stabilize the structure and eliminate brittleness. There are many auto parts, in order to retain the toughness of the core, but also to change the surface structure to improve the hardness, it is necessary to use surface high-frequency quenching or carburizing, cyanidation and other heat treatment processes.
