Synergistic enhancement of strength and ductility in Fe–10Mn-0.4C steel via short-time partitioning and cold rolling

In the conventional preparation of medium-manganese high-strength steel, hot rolling or cold rolling processes are primarily employed, interspersed with isothermal tempering to ensure the mechanical properties of the steel. This study aims to enhance austenite stability by controlling the partitioning time to promote carbon diffusion from supersaturated martensite into retained austenite. Subsequent cold rolling induces deformation-induced martensitic transformation in the metastable austenite, converting it into newly formed martensite. Concurrently, this process generates defects such as twin dislocations within the retained austenite, enhancing its mechanical stability and refining the microstructure. Finally, tempering eliminates residual stresses to restore toughness while promoting partial carbon segregation from the newly formed martensite back into the retained austenite, ultimately stabilizing a portion of the austenite. Through an optimized quenching-alloying-cold rolling-tempering process, Fe–10Mn-0.4C steel with outstanding strength and toughness was successfully produced. Research indicates that under optimal process conditions, this steel grade achieves a yield strength of 1450 MPa, a tensile strength of 1720 MPa, and an elongation of 22.5 %. Short partitioning times enhance the stability of retained austenite, whereas excessively long partitioning times lead to performance deterioration.