Achieving 2.6 GPa tensile strength with outstanding ductility in high-carbon low-alloy steel

• A high-carbon low-alloy steel achieves a tensile strength of ~2.6 GPa with a total elongation of 12%, demonstrating outstanding strength–ductility synergy. • Refinement of prior austenite grains promotes dislocation martensite over brittle twinned martensite, enhancing ductility without sacrificing strength. • Suppressing the Mf temperature to sub-room temperature via combined alloying (C, Ni, Mn, Si, Cr, Mo) enables ~15 vol% retained austenite at room temperature. • The retained austenite activates the transformation-induced plasticity (TRIP) effect, providing a cost-effective and industrially viable alternative to complex Q&P processes and Mn segregation concerns.