Effect of Deepth QPQ Process on Microstructure of 3Cr13 Steel

Taking 3Cr13 martensitic stainless steel as materials,based on the deepth QPQ(quench polish quench)complex salt bath treatment,the effects of nitriding temperature,nitriding time and CNO-concentration on the microstructure of nitriding layer of the stainless steel by QPQ complex salt bath treatment were studied.The microhardness of diffusion layer was measured by digital micro-hardness tester.The treated surface microstructure was observed by SEM,meanwhile,the thickness and the quality of the compound-layer were also analyzed.The results show that: with the nitriding temperature or nitriding time increasing the depth of nitriding layer increases;in the nitriding temperature of 630 ℃ for 2 h,the depth of nitinding layer is about 97μm;with the nitriding temperature increasing,the surface hardness of the sample at 600℃ after the downward trend,there are loose layer formation.The effects of CNO-concent on the nitriding layer is significant,particularly reflected in the diffusion layer.The effect of CNO-concent on the surface hardness of the sample is little.