Effect of isothermal time and alloy elements on bainitic transformation below Ms in medium Mn Steels

Abstract

For Fe-C-Mn-Si system, the effect of cobalt, aluminium, manganese and isothermal time on the bainitic transformation, especially the kinetics of isothermal bainitic transformation below Ms temperature, was studied by dilatometry and scanning electron microscope (SEM). The microstructure of the steels at room temperature was observed and the results showed that cobalt could increase the transformation rate of isothermal bainitic transformation below Ms temperature and aluminium had the opposite effect. And higher content of manganese could also lead to slower bainitic transformation. The incubation time of isothermal bainitic transformation almost disappeared below Ms temperature. The bainitic transformation plays an important role on the redistribution of carbon, so it could be used to improve the austenite stability and increase the plasticity of the steel.