Low pressure plasma arc source ion nitriding of austenitic stainless steel

A series of low pressure plasma arc source ion nitriding experiments has been conducted on AISI 304 stainless steel at temperatures ranging from 350 to 460°C in an N2–H2 gas mixture. The structure and composition of the plasma nitrided layers were studied by optical metallography, X-ray diffraction (XRD) and Auger electron spectroscopy (AES). The thickness of the nitrided layer depends on the plasma nitriding temperature. After 2 h of nitriding at 420°C, a 12 μm nitrogen supersaturated austenite nitrided layer with nitrogen content up to 45 at% on the surface was formed. The hardness values of the nitrided layer measured are in the range of 4.6 GPa for the sample nitrided at 350°C to 12.0 GPa for the sample nitrided at about 420°C.