Tuning the pitting performance of a Cr-13 type martensitic stainless steel by tempering time

The microstructural evolution and pitting performance of a Cr-13 type martensitic stainless (MSS) undergone tempering at 500 °C for different time are investigated via electron microscopies and electrochemical measurements. The precipitation sequence of carbides in MSSs tempered for 0.5–48 h is θ-M3C→10 nm sized M23C6→100 nm sized M23C6. Severe corrosion occurred when the MSS were tempered within the time window of 2–24 h. In contrast, the passivation of MSSs was recovered as the tempering time increased to 48 h or longer. Our finding in this work provides a new path for optimizing the corrosion resistance of MSSs via tempering time.