Surface modification of 2205 duplex stainless steel by low temperature salt bath nitrocarburizing at 430 °C

2205 stainless steel was modified by salt bath nitrocarburizing at 430 °C in this study. The microstructure, surface hardness and erosion–corrosion resistance were systematically evaluated. Salt bath nitrocarburizing at 430 °C can form a nitrocarburized layer, and with the treated time prolong, the thickness of the layer increased. By nitrocarburizing within 8 h, only expanded austenite (S phase) formed. With treated time increased, CrN gradually diffused from the places where there were ferrite grains in the layer before nitrocarburizing. Besides, the depth increased with the nitrocarburized time and the layer grew approximately conforms to the parabolic rate law. Salt bath nitrocarburizing can effectively improve the surface hardness of 2205 DSS. The erosion–corrosion resistance was improved by salt bath nitrocarburizing and the 16 h treated sample had the best erosion–corrosion behavior.