Achieving ultrahigh strength-ductility synergy in 2.2 GPa medium-Mn steel via controlled martensite variant selection

A hot-rolled medium-Mn steel achieves an exceptional strength—ductility synergy: yield strength of 1.8 GPa, ultimate tensile strength of 2.2 GPa, and total elongation of 18%. This performance results from an architectural design in which banded prior austenite promotes V1/V4 martensite variants that activate intragranular slip, while nano-sized retained austenite, stabilized via carbon partitioning, supplies sustained transformation-induced plasticity. The work establishes an intrinsic link among prior austenite structure, martensite variant selection, and slip system activation, providing a new theoretical basis for overcoming the strength—ductility trade-off.