Effect of tempering temperature on the microstructure, corrosion resistance, and antibacterial properties of Cu‐bearing martensitic stainless steel

Abstract

AbstractIn this study, the effects of tempering temperature on the microstructure, hardness, antibacterial performance and corrosion resistance of Cu‐bearing 5Cr15MoV martensitic stainless steel (5Cr15MoV‐Cu MSS) were investigated using an optical microscope, a scanning electron microscope, X‐ray diffraction, a transmission electron microscope, an antibacterial test, electrochemical measurements, and the salt spray test. The results showed that the hardness curve had a saddle shape and its values reached the peak value after tempering at 500°C, due to the secondary hardening effect by the precipitation of tiny secondary carbides and Cu‐rich precipitates. In addition, the antibacterial results also showed excellent antibacterial performance against Escherichia coli at 500°C because of the formation of Cu‐rich precipitates. Results of corrosion tests indicated that the corrosion resistance decreased gradually with an increase of the tempering temperature. In particular, the passivation did not occur when the tempering temperature was above 500°C, which may be related to the Cu‐rich precipitates and Cr depletion.