The reason why quenched steel has good performance, heat treatment is an unavoidable process. Common heat treatment processes for quenched steelinclude annealing, quenching, and tempering. Annealing is before the cutting process, the purpose is to reduce the hardness of the metal material, improve the plasticity, in order to facilitate cutting or pressure processing, reduce the residual stress. Quenching and tempering are all together. After quenching, direct tempering is performed before finishing. The purpose of quenching is to make the steel obtain the required martensite structure and improve the hardness, strength and wear resistance of the workpiece. Prepare heat treatment and so on. The purpose of tempering: Mainly to eliminate the stress generated during the quenching of steel, so that the steel has high hardness and wear resistance, and has the required plasticity and toughness. After heat treatment, the hardness of the workpiece is generally above HRC45, and some even reach HRC60 or above. Different workpieces have different work properties, so the hardness after heat treatment is also different. For example, the hardness of automotive gearbox heat treatment is generally in HRC58-63. The hardness of the slewing bearing after heat treatment is between HRC 47-55, and the hardness of the ball screw after heat treatment is generally between HRC 60-62.