Effect of Carbon Content in Retained Austenite on the Dynamic Tensile Behavior of Nanostructured Bainitic Steel

Results of dynamic tensile testing of three-step low-temperature-transformed nanostructured bainitic steel and quenching and partitioning martensitic steel at different strain rates (0.1-500 s(-1)) are reported here. The results showed that the high carbon film-like austenite was much more stable than the low carbon blocky austenite during deformation. The nanostructured bainite steel exhibited the more remarkable dynamic tensile properties due to the better transformation-induced plasticity effect and strain rate hardening effect exhibited by stable film-like retained austenite. The big gap in engineering stress and strain curves occurred at a higher strain rate (100-200 s(-1)) for the nanostructured bainite steel because of the better stability of film-like austenite. Therefore, the present study is able to assist in explaining the effect of carbon content in retained austenite on the dynamic tensile properties and understanding the microstructure property relationship in complex steels.