A simultaneously improved strength and ductility on medium Mn TRIP steel designed by pre-twinning strategy based on SFE controlling

In this work, we developed a strategy based on SFE controlling to improve the mechanical properties of a medium Mn steel. Two successive cycles of deformation were conducted in the stacking fault energy ranges dominated by dislocation slip and twinning deformation, which developed steel with high density dislocations and nanotwins. Dislocation strengthening results in high yield strength. Meanwhile, martensitic transformation within nanotwins provides continuous hardening capacity and consequently high strength and acceptable ductility via alleviating shear strain accumulation and retarding crack initiation.