Quenching 

Steel is heated to the point above a certain temperature, keep a certain amount of time, then in water (oil) with appropriate speed cooling for martensite and bainite heat treatment process is called hardening of the organization. Quenching and annealing, normalizing treatment on craft is the main difference between the cooling speed, the purpose is to obtain martensitic structure. How to look from the bearing number bearing classification 

Tempering 

Steel hardening, then heating and heat preservation time, and then cooled to room temperature of heat treatment process called tempering. According to the different tempering temperature, tempering can be divided into low temperature tempering, medium temperature tempering and high temperature tempering 3 kinds. So commonly used by general medium carbon steel and medium carbon alloy steel quenching after high temperature tempering treatment. Axial parts of this application. How to look from the bearing number bearing classification 

Annealing 

The steel is heated at a certain temperature after heat preservation, and cooling temperature and room temperature. 

Annealing have complete annealing, spheroidizing annealing, the stress relieving several ways. 

Is completely annealing heat the steel to the predetermined temperature, heat preservation and then cooling. This can reduce the hardness of steel. 

Spheroidizing annealing is heated to a temperature of 750 degrees, insulation first, then cooled to 500 degrees, this approach is used to reduce the hardness of steel is often used in high carbon steel. 

Low temperature annealing is hang steel heating to 500 ~ 500 degrees, with slow cooling furnace insulation first, then to 300 degrees, can eliminate the internal stress of the metal after cooling. 

Is the fire 

Steel is heated to 30-50 ℃, in normal temperature cooling called normalizing. 

Normalized to refine the organization and the steel performance is close to equilibrium.