Structure and properties of plasma nitrided austenitic stainless steel

304 austenitic stainless steel was nitrided by d.c. plasma at the temperature of 400 to 525degreesC and the cathode potential of 500 to 1400V. The thickness of nitrided layer treated at high voltage and low gas pressure was about 2.5 times thicker than that of regular nitriding. Moreover, a single-phase layer known as 'S phase' was obtained at low temperature with high voltage and low pressure, differing to regular treatment in which there usually is CrN precipitation. The tribological property of samples with thicker layer was good under ball-on-disk wear test. And the corrosion resistance with the single phase layer was not affected by nitriding, while that of others was poorer than untreated stainless steel.