Inducement of bainite and carbide transformation from retained austenite based on a high strain rate

As-received ultrahigh 300 M strength steel was impacted at strain rates of 1 × 103 and 4 × 103 s–1. At the strain rate of 1 × 103 s–1, the retained austenite transformed into upper bainite and M7C3 precipitates. Fine Mo2C carbides precipitated in the bainitic ferrite matrix in addition to upper bainite during deformation contribute to the strengthening effect at a relatively high strain rate of 4 × 103 s–1.