Influence of plasma nitriding on dry wear, corrosion and tribocorrosion performance of 17‐4 precipitation hardening stainless steel

Abstract Plasma nitriding treatment of 17‐4 precipitation hardening stainless steels was carried out at 400 °C and 450 °C using a direct current unit. The nitriding layer thicknesses of the plasma nitrided at 400 °C and 450 °C were measured as 37.29 μm and 49.97 μm, respectively. The plasma nitrided sample at 400 °C presented dominant martensite and retained austenite phases; however, the height of main martensite diffraction peaks increased at 450 °C. The hardness results demonstrated that the samples at 400 °C and 450 °C were 2.9 and 3.1 times as hard as the untreated sample, respectively. The wear rate values of the sample at 450 °C showed a decrease by 19 % in the corrosive salt solution and 57 % in the dry‐sliding condition compared with that of untreated sample. The corrosion potential of the sample at 400 °C had more positive potential value and lower current density value than those of at 450 °C. The corrosion resistance of the sample at 400 °C improved due to the positive effect of the retained austenite phase. In this study, the wear was more dominant rather than corrosion, therefore plasma nitrided sample at 450 °C showed the best dry wear and tribocorrosion resistance.