Low temperature plasma surface alloying of medical grade austenitic stainless steel with carbon and nitrogen

Abstract

Low temperature surface alloying with either nitrogen (nitriding) or carbon (carburising) has been successfully employed in hardening AISI 316. However, little work has been directed towards low temperature plasma surface alloying with both nitrogen and carbon simultaneously. In addition, little or no research has been conducted on the surface modification of medical grade austenitic stainless steels, such as ASTM F138 and F1586. In the present study, plasma surface alloying treatments have been conducted on medical grade ASTM F138 and ASTM F1586 as well as on engineering grade AISI 316 for comparison. Systematic materials characterisation was carried out using optical microscopy, glow discharge optical emission spectroscopy (GDOES) and X-ray diffraction (XRD). The three stainless steels had similar response to the plasma alloying treatments. At a temperature of 425°C plasma surface alloying with both carbon and nitrogen can effectively increase the surface hardness and wear resistance of the three austenitic stainless steels without compromising the corrosion resistance of the alloy.