Influence of microstructure on the corrosion behavior of super 13Cr martensitic stainless steel under heat treatment

Abstract The effect of microstructure on the corrosion characteristics of super 13Cr martensitic stainless steel (S13Cr MSS) under heat treatment was investigated. The results revealed that the Ni enriched reversed austenite content in the tempered steel increased as the tempering temperature increased. No Mo-rich intermetallic compounds and reversed austenite were found in the quenched steel. The Mo-rich intermetallic compounds adversely affected the protective properties of the corrosion film because the Mo-depleted regions adjacent to the compounds had approximately 7 mV Volta potential lower than steel matrix, destroying the corrosion film stability. However, the reversed austenite benefitted on the corrosion film due to it inhibiting further corrosion of S13Cr MSS and enhancing the corrosion film stability. Accordingly, the quenched steel without Mo-rich intermetallic compounds had the highest corrosion resistance and the corrosion resistance of the tempered steel increased with an increasing tempering temperature.