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%).

This study examines the electrochemical behavior and slow strain rate tensile (SSRT) properties of 67Si2CrNiAlMnMoCu steel featuring a multiphase nanobainitic microstructure consisting of bainitic ferrite (BF), retained austenite (RA), and martensite (M). Electrochemical measurements reveal that both the corrosion tendency and dissolution rate decrease with extended austempering time, with the sample austempered at 220 °C for 21 h showing the lowest corrosion susceptibility. SSRT results indicate that specimens with a nearly fully bainitic microstructure exhibit increased strength sensitivity to stress corrosion. Notably, the specimen austempered at 240 °C for 9 h demonstrates excellent corrosion resistance while retaining favorable overall mechanical properties, exhibiting a tensile strength-based stress corrosion cracking sensitivity coefficient as low as 4.1%.