An investigation on the microstructure, tribological and corrosion performance of AISI 321 stainless steel carbonitrided by RF plasma process

An anticorrosive and wear-resistant superficial top layer was distinctly produced in AISI 321 austenitic stainless steel by rf plasma carbonitriding. Details about the elemental distribution profiles and the microstructure of the carbonitrided samples, as a function of treatment temperature, were characterized by glow discharge optical spectroscopy (GDOS), grazing incidence X-ray diffraction (GIXRD) and optical microscopy (OM). The tribological behavior was investigated using a ball-on-disc tribometer. Further the corrosion performance of the treated samples compared to the untreated one was examined using electrochemical tests with potentiodynamic anodic polarization curves. Glow discharge optical spectroscopy indicated that, the nitrogen and carbon contents diffused into the surface during carbonitriding were found to be treatment temperature dependent. The lowest friction coefficient and superior wear resistance in the presence of excellent corrosion resistance were observed for the samples carbonitrided at treatment temperature of 818–863 K. According to Arrhenius plot analysis, the activation energy was 4 eV/atom while the effective diffusion coefficient was found to be 199.3 × 102 μm2/h.