A comparative study of ion beam nitriding of single-crystalline and polycrystalline 316L austenitic stainless steel

Abstract

Nitriding of an austenitic stainless steel (ASS) at moderate temperature (400 °C) increases significantly its hardness without loss of corrosion resistance. This study presents the first comparison between single crystalline ([001], [011] and [013] orientations) and polycrystalline 316L ASS ion beam nitriding. The current density, ion energy and temperature were 0.5 mA·cm −2, 1.2 keV and 400 °C, respectively. The nitrogen distribution profiles were measured by nuclear reaction analysis (NRA). A notable difference of nitrogen penetration between polycrystalline and single-crystalline samples is observed, depending on the orientation of the single crystals. The nitrogen penetration is higher for [100] and [013] oriented single crystals. X-ray diffraction (XRD) reveals the presence of the γ N phase in both types of samples. Moreover, it shows that the nitrided layer in single crystals exhibits disorientations in relation to the matrix.