The wear and corrosion properties of stainless steel nitrided by low-pressure plasma-arc source ion nitriding at low temperatures

Low pressure plasma are discharge-assisted nitriding of AISI 304 austenitic stainless steel is a process that produces surface layers with useful prop erties such as a high surface hardness of approximately 1500 Hv(0.1) and a high resistance to frictional wear and corrosion. The phase composition, th e thickness, the microstructure and the surface topography of the nitrided layer, as well as its properties, depend essentially on the process paramet ers. Among them, the processing temperature is the most important factor fo r forming 21 hard layer with good wear and corrosion resistance. Nitriding austenitic stainless steel at approximately 420 degrees C for 70 min can pr oduce a thin layer of 7-8 mu m with very high hardness and good corrosion r esistance on the surface. The microstructure was studied by optical microsc opy and both glancing angle and conventional Bragg-Brentano (theta-2 theta) symmetric geometry X-ray diffraction (XRD). The formation of expanded aust enite was observed. Measurements of the wear depths indicated that the wear resistance of austenitic stainless steel can be improved greatly by nitrid ing at approximately 420 degrees C using low-pressure plasma-are source ion nitriding. (C) 2000 Elsevier Science S.A. All rights reserved.