High magnetic field enhanced strength-ductility synergy in a Q&P processed medium-Mn steel

Improving yield strength often reduces uniform elongation, limiting the optimization of the strength-ductility balance. This study demonstrates for the first time that applying a 10 T magnetic field during the heating and quenching stage of quenching and partitioning (Q&P) processing can enhance the yield strength of a medium-Mn steel by 43% (to 1180 MPa) without sacrificing its ultimate tensile strength and uniform elongation (~22.7%). This is primarily associated with the magnetic-field-induced increase in the driving force for martensitic transformation during quenching, together with enhanced elemental redistribution. This work provides direct evidence for the optimized application of a high magnetic field in Q&P processing, offering a promising route to mitigating the strength-ductility trade-off.