Stabilizing austenite via intercritical Mn partitioning in a medium Mn steel

In this study, a novel processing route of intercritical Mn partitioning is proposed to stabilize the reverted austenite in a medium Mn steel. The Fe-5Mn-0.2C-1.5Al (wt.%) steel is annealed unceasingly at two intercritical temperatures to produce a compositional core-shell structured reverted austenite which consists of a core in low Mn content and a shell in relatively high Mn content. This distinctive microstructure can not only allow much more retained austenite to be obtained compared with the conventional processing route, but also produce active transformation induced plasticity effect over a broad strain range, leading to excellent mechanical properties of high strength and enhanced ductility.