Abstract: Plasma nitriding, liquid nitriding and gas nitriding were used to modify the surface of corrosion-resistant and heat-resistant martensitic heat-stable stainless steel 1Cr12Ni2WMoVNb. The hardness, microstructure, phase change and brittleness of the stainless steel under the three different nitriding methods were studied, and the corrosion resistance and high temperature wear resistance of the steel nitrided by the three nitriding methods were compared. The results show that the surface hardness of the steel can be greatly improved by this three nitriding methods, and the microstructure of the nitriding layer is roughly the same, but the surface phase is different, the surface phase after plasma nitriding is mainly Fe₄N and a small amount of CrN phase, after liquid nitriding is Fe₃O₄ and ε phase, and after gas nitriding is Fe₃O₄, Fe₄N and a small amount of ε phase. The high temperature wear resistance, especially when the temperature is in the range of 500-600 ℃, can be greatly improved by this three nitriding methods, but the corrosion resistance is all reduced.

Key words: plasma nitriding, liquid nitriding, gas nitriding, wear, corrosion resistance