Abstract: After T92 steel was tempered at different tempering temperature and by different cooling methods, the variations of properties of T92 steel, such as the microstructure, the hardness and the mechanical properties, were detected. The influence of the tempering treatment on the characteristics of P92 steel was researched. The experiment results show that after high temperature tempering (830℃), the microstructure of the T92 steel changed from martensite into ferrite and carbide gradually, the tensile strength and the shock absorbing energy of the steel did not reduce, but the hardness and the yield strength of the steel reduced obviously (lower than the lower limit value required by relevant standard). On the side, in high temperature tempering process below AC1 line, the cooling speed does not much impact the properties and the microstructure of the material.

Key words: P92 steel, tempering treatment, mechanical property, microstructure