Abstract: H13 steel with different contents of rare earth Ce was austenitized at different temperatures for 30 min, air-cooling hardened, and then twice tempered at different temperatures for 2 h, air cooling, and then the structure observation and hardness test were carried out. The results shows that when the quenching temperature reaches 1040 ℃, the carbide on the matrix structure and grain boundary is reduced, and the lath martensite is clearer. When the tempering temperature is 580 ℃, the microstructure is tempered martensite + tempered troostite. When the tempering temperature exceeds 600 ℃, and the carbides gather and grow. Therefore, the best heat treatment process is quenched at 1040 ℃ + twice tempered at 580 ℃. When the rare earth Ce content is 0.026%, the grain of the tested steel is the finest, the structure is the most uniform, the hardness is the highest, the quenching hardness is 650.6 HV30, and the tempering hardness is 391.4 HV30.

Key words: rare earth Ce, quenching temperature, tempering temperature, hardness