Effect of aging treatment on the corrosion resistance of 15-5 PH stainless steel: Insights from the role of reversed austenite

The 15-5 PH stainless steel typically requires aging to enhance its mechanical properties. However, the formation of reversed austenite during aging can affect its corrosion resistance, the underlying mechanism of which remains poorly understood. In this study, the reversed austenite content was modified by aging the samples at various temperatures, and the resulting microstructures and corrosion behaviors were analyzed. The results showed that the reversed austenite content initially increased with the aging temperature and then decreased at higher temperatures. The corrosion resistances of the aged samples were lower than that of the as-quenched sample, and this was primarily attributed to carbide precipitation. In addition, the presence of reversed austenite reduced the risk of passive film rupture, thereby enhancing its integrity and continuity. However, at excessively high aging temperatures, further elemental diffusion led to transformation of the reversed austenite into martensite, which reduced the corrosion resistance. These findings elucidate the mechanism by which reversed austenite influences the corrosion behavior of 15-5 PH martensitic stainless steel, thereby offering new perspectives for the optimization of its heat treatment process.