Effect of Austempering Temperature on Stress Corrosion Resistance of 52CrMoV4 Spring Steel

Stable service performance of spring steel under complex working conditions is essential, and under the synergistic effect of corrosive environment and stress, stress corrosion cracking is very likely to occur. Austempering can change the microstructure of spring steel and thereby improve its stress corrosion sensitivity. In this study, methods such as scanning electron microscopy and slow strain tensile tests were adopted to investigate the effects of different austempering temperatures on the microstructure and stress corrosion resistance of 52CrMoV4 spring steel. The results show that crack initiation during stress corrosion cracking in the test steel is mainly related to anodic dissolution. The coarsening of bainite laths and the increase in the area of martensite–austenite islands accelerate stress corrosion cracking once stress concentration occurs. The steel austempered at 310 °C has the best resistance to stress corrosion, with a stress corrosion sensitivity value of only 2.4%, which is much lower than those of specimens under traditional processes (15.5–23.7%).