Optimum design of the gas nitriding technological parameters of H13 steel

The gas nitriding technology of H13 steel was studied by an orthogonal test.For obtaining high surface hardness and great thickness,the main factors which affect the nitriding layer structure and properties were analyzed,and the optimized parameters were obtained.The microstructure of the nitriding layer of H13 tool steel after gas nitriding were studied by OM and X-ray,the surface hardness of samples were measured by microhardness tester.The results showed that the main parameters of nitridation process which affect the surface hardness and nitrided case depth are nitriding temperature and decomposition rate of ammonia.The maximum thickness of nitride layer and microhardness are 244.3μm and 1212.6Hv respectively.The optimum technical parameters are that tempering temperature before nitriding,nitriding temperature,time,and decomposition rate of ammonia are 560℃,535℃,15h,50%,respectively.