Liquid Induction Carburized/Nitriding/ Carbonitriding Of Low/Medium Carbon Alloy Steel

This paper studies the liquid induction nitriding, carburizing, carbonitriding and nitrocarburizing technology. Liquid induction thermochemical is based on the induction heating technology with the advantages of processing time, energy efficient, low environmental pollution, etc. It’s suitable for processing shaft parts. Nitrocarburizing layer was prepared on 38CrMoAl steel and 20CrMnTi steel by liquid induction nitrocarburizing technology in methanamide solution. Carbonitriding layer was prepared on 45Mn2 steel and 20CrMnTi steel by liquid induction carbonitriding technology in methanamide solution. Carburizing layer was prepared on 20CrMnTi steel by liquid induction carburizing in Quenching oil. Microstructure and morphology of surface layer were investigated by OM and SEM. Microhardness variation with the depth was measured by microhardness tester. Phase of surface layer was analysised by XRD. The relationships of layer organization and hardness with processing time and processing temperature were studied. The optimum process parameters were determined.The results show that 38CrMoAl was treated by liquid induction nitriding and nitrocarburizing at 500℃～650℃. The hardness of layer is 800HV0.1 and the thickness of layer is 100μm. The phase of layer is mainly ζ(Fe2N), ε(Fe2,3N), γ□(Fe4N), α、Fe3C.45Mn2 was treated by liquid induction carbonitriding at 900℃ for 5min. Hardness of carbonitriding layer is 700HV0.3 and thickness of carbonitriding layer is 330μm.20CrMnTi was treated 5min at 530℃～680℃. The layer of nitriding is double white layer. The hardness of double white layers is about 300～50HV0.1 at 530℃～590℃. The hardness of nitrocarburizing layer is more than 550HV0.1 at 600℃～680℃ for 5min. Thickness of carbonitriding layer is more than 100μm at 700℃～760℃ and 830℃～880℃ for 5min. Hardness of carbonitriding layer is 650HV0.3. In addition, carburizing layer is prepared by liquid induction carburizing at 800℃～930℃. Thickness of carburizing layer is 150μm at 880℃ and 250μm at 930℃ for 10min. Hardness of carburizing layer is 800HV0.3. Orgnization of carburizing layer is stable acicular martensite.