Modulating Mechanical Properties of Fe–0.35C–3.2Al–5Mn Hot‐Rolled Steel by Combining Twinning‐Induced Plasticity plus Transformation‐Induced Plasticity Effect

The microstructures and mechanical properties of Fe–0.35C–3.2Al–5Mn (in wt%, same later) hot‐rolled medium‐manganese steels are systematically investigated. The results show that ultrafine‐grained duplex phases with bimodal morphologies of lath and equiaxed are obtained with intercritical annealing at 750 °C for 1 h, along with ultimate tensile strength of 950 MPa and total elongation of 71.2%, attributed to the dislocation slip and deformation of ferrite matrix, accompanied by the synergetic twinning of retained austenite plus transformation of retained austenite to martensite. The newly developed medium‐manganese steels, which exhibit an excellent product of ultimate tensile strength and total elongation of 67.6 GPa·%, demonstrate great practical applications.