复合化学热处理对G13Cr4Mo4Ni4V钢组织和硬度的影响

采用扫描电镜、洛氏硬度计和维氏显微硬度计研究了渗氮140 h对渗碳+淬火+回火G13Cr4Mo4Ni4V钢微观组织及硬度的影响。结果表明,渗碳+淬火+回火后G13Cr4Mo4Ni4V钢有效渗碳层深度为1.45 mm,渗碳层最高硬度为785 HV,心部硬度为420 HV,经渗氮处理后有效渗碳+渗氮层深度降为1.34 mm,渗氮层深度为0.22 mm,渗氮层最高硬度可达到948 HV,心部硬度为451 HV,较未渗氮试样硬度略有提高。渗碳+淬火+回火和添加渗氮处理后G13Cr4Mo4Ni4V钢的表面洛氏硬度相当,均在62~65 HRC 之间,但渗氮处理后试样的硬度波动性较大。添加140 h渗氮的渗碳+淬火+回火后G13Cr4Mo4Ni4V钢实现了“表面硬心部韧”的目标,渗氮层深度满足工程需要,但添加渗氮处理后G13Cr4Mo4Ni4V钢在渗碳层和渗氮层出现类网状碳化物,因此在渗氮过程中需要综合考虑渗氮层深度和微观组织,以获得良好的综合力学性能。

Effect of compound chemical heat treatment on microstructure and hardness of G13 Cr4 Mo4 Ni4 V steel

Effect of 140 h nitriding on the microstructure and hardness of carburized+quenched+tempered G13Cr4Mo4Ni4V steel was studied by using SEM, Rockwell hardness tester and Vickers microhardness tester. The results show that the depth of the effective carburized layer of G13Cr4Mo4Ni4V steel after carburizing+quenching+tempering is 1.45 mm, the highest hardness of the carburized layer is 785 HV, and the hardness of the core is 420 HV. The depth of the effective carburized and nitrided layer after nitriding treatment is reduced to 1.34 mm, the depth of nitrided layer is 0.22 mm, the highest hardness of the nitrided and nitrided layer can reach 948 HV, and the hardness of the core is 451 HV. Nitriding does not significantly improve the hardness of the core of the specimen. The surface Rockwell hardness of the G13Cr4Mo4Ni4V steel after carburizing+quenching+tempering and after nitriding treatment is similar, which is between 62 and 65 HRC, but the hardness of the specimen after nitriding treatment fluctuates relatively larger. The 140 h nitriding of carburized+quenched+tempered G13Cr4Mo4Ni4V steel achieves the goal of “hard surface and tough core”. The depth of the nitrided layer meets the engineering needs, but the network-like carbonization appears in the carburized and nitrided layer of the steel after nitriding treatment, so in the nitriding process, it is necessary to comprehensively consider the depth and microstructure of the nitriding layer to obtain good comprehensive mechanical properties.