Effect of low-temperature plasma nitriding on the sliding wear behavior of 17–4PH stainless steel in high temperature water

Plasma nitriding significantly enhances the tribological performance of 17–4 precipitation hardening (PH) stainless steel. However, the wear resistance of plasma-nitrided 17–4PH stainless steel in high temperature water remains unpredictable due to the complex interaction between wear and corrosion under such conditions. In this study, we conducted a wear test on nitrided 17–4PH stainless steel in high temperature water to evaluate its wear behavior. Our findings demonstrate that nitriding treatment improves wear resistance. Additionally, the wear mechanism shifts from delamination wear to oxidational wear after nitriding. The interaction between wear and corrosion was revealed. The subsurface of the worn scar undergoes plastic deformation, which accelerates corrosion. However, the oxide scale formed by corrosion can act as a lubricant to mitigate wear. For non-nitrided specimen with lower hardness, delamination cracks initially form in the subsurface, with the crack surfaces subsequently oxidizing and filled with debris. Material loss results from the peeling of the delamination. In contrast, for nitrided specimens with higher hardness, the subsurface of the worn scar is composed of an oxidation layer that detaches under mechanical wear, leading to material loss.