Low-temperature plasma nitrocarburizing of 15 − 5 PH stainless steel for optimized surface hardness and corrosion resistance

Abstract This study examines the influence of low-temperature plasma nitrocarburizing (LT-PNC) on the surface properties of 15 − 5 precipitation-hardening (PH) stainless steel. The material was treated at three temperatures, specifically 410 °C, 430 °C, and 460 °C, for duration of fifteen hours. The resulting surfaces were characterized by X-ray diffraction, microhardness measurements, salt fog testing, and potentiodynamic polarization. Plasma nitrocarburizing (PNC) produced a substantial increase in surface hardness, reaching approximately 70 HRC compared with the untreated value of about 42 HRC. At treatment temperatures of 430 °C and above, chromium nitride (CrN) formation was observed, which led to chromium depletion and a subsequent decline in corrosion resistance. In contrast, the sample processed at 410 °C achieved a balance between enhanced hardness and the preservation of corrosion resistance. Overall, the findings confirm that LT-PNCis an effective method for improving both durability and corrosion performance of 15 − 5 PH stainless steel, indicating its suitability for aerospace and other high-performance engineering applications.