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

Abstract

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.

Mechanism and Application of Reverse Austenitic Transformation in Medium Mn Steels: A Systematic Review

“…Grain boundaries are the most common nucleation sites of austenite in MMS. [19][20][21][22] The classical nucleation theory suggests that the nucleation at grain boundaries could reduce the interfacial energy barrier, thereby reducing the nucleation formation energy. [23][24][25] Alternatively, the recently developed nucleation models indicate that the Mn segregation into boundaries is responsible for this kind of austenitic nucleation because it leads to the higher thermodynamic driving force for the reverse transformation in the interfacial region.…”