According to the different performance requirements of the workpiece and the different tempering temperature, tempering can be divided into the following types:

（1） The microstructure of low temperature tempering (150-250 ℃) is tempered martensite. The purpose is to reduce the internal stress and brittleness of quenched steel on the premise of maintaining its high hardness and wear resistance, so as to avoid cracking or premature damage. It is mainly used in various high carbon cutting tools, measuring tools, cold stamping dies, rolling bearings and carburized parts. The hardness after tempering is generally hrc58-64.

（2） The microstructure of medium temperature tempering (350-500 ℃) is tempered troostite. The aim is to obtain high yield strength, elastic limit and high toughness. Therefore, it is mainly used for the treatment of various springs and hot working dies, and the hardness after tempering is generally hrc35-50.

（3） The microstructure of high temperature tempering (500-650 ℃) is tempered sorbite. The combination of quenching and high temperature tempering is usually called quenching and tempering treatment. Its purpose is to obtain comprehensive mechanical properties with good strength, hardness, plasticity and toughness. Therefore, it is widely used in automobile, tractor, machine tool and other important structural parts, such as connecting rod, bolt, gear and shaft. The hardness after tempering is generally hb200-330.