Effect of ionic plasma nitriding process on the corrosion and micro-abrasive wear behavior of AISI 316L austenitic and AISI 470 super-ferritic stainless steels

Abstract

The aim of this work was to study the influence of thermochemical treatment of ionic plasma nitriding on the resistance to micro-abrasive wear and to the corrosion process of AISI 316L and AISI 470 stainless steels. The thermochemical treatment was performed at different times and temperatures with a gas mixture of 25% H2 and 75% N2. The treated materials were characterized by using optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD), microhardness tests, micro-abrasive wear tests (MAWTs) and corrosion tests. The results show an increase in the thickness of the layer formed by increasing treatment time and in the wear resistance of the materials studied. Temperatures exceeding 450 °C favor the formation chromium nitrides, which, for being very hard broke making the formed layer brittle decreasing the wear resistance of the material. In addition, the formation of these phases substantially decrease the corrosion resistance of stainless steels. Keywords: Corrosion, Wear tests, Expanded ferrite, Expanded austenite