Abstract: In order to improve the comprehensive performance and surface wear resistance and fatigue resistance of the 30CrMoV9 steel for hydraulic piston pump, the quenching and tempering process and the gas nitriding process after rough machining of the 30CrMoV9 steel were studied, and the quenched and tempered hardness, nitrided layer depth, nitrided microstructure and nitrided layer hardness were tested. The results show that after quenching at 900 ℃ and tempering at 630-640 ℃, the tested steel can meet the requirement of hardness in the range of 28-35 HRC. After gas nitriding, the average surface hardness of the quenched and tempered 30CrMoV9 steel can reach more than 750 HV0.5, which can effectively improve the contact fatigue strength of parts.

Key words: 30CrMoV9 steel, quenching and tempering, gas nitriding, comprehensive performance, microstructure