Enhanced stability of retained austenites in quenched 25SiMn2MoV steel by electro-pulsing current

In this contribution, an electro-pulsing current is applied to 25SiMn2MoV steel to obtain substantial retained austenite contents. Interestingly, after only 440 m s, retained austenite with a volume fraction higher than 10% is obtained via electro-pulsing. In addition, the Ms temperatures of the samples in the different electro-pulsing treated states are all much lower than room temperature, which implies the sufficient stability of this retained austenite. By choosing different initial states, the morphology and content of retained austenite can also be adjusted. It is found that when the initial state is eutectoid, the morphology of the retained austenite formed during electro-pulsing is globular, and the volume fraction is also higher. While the initial state is quenched, the retained austenite exhibits a layered morphology, and the content is relatively low. The mechanical properties indicate that compared with traditionally treated samples, the electro-pulse-treated samples possess a better strength and ductility. In addition, due to the TRIP effect induced by retained austenite, the ability of the resulting materials to prevent crack propagation and work-hardening is also improved. This work proposes a novel method to efficiently obtain adequate contents of retained austenite in low alloy steels and paves a new way for developing new low alloy steels with good properties.