Improvement of strength-ductility balance of Fe-Mn-Al-C-based austenitic steel via tuning rolling strain

Abstract

In this work, a typical heterostructure for a Fe-Mn-Al-C-based austenitic steel is processed by a simple cold-rolling process. As cold-rolling strain increasing (20 %→80 %), the steel exhibits an increasing in the dislocations and shear bands, accompanied by a reduction in the fraction of the region with low dislocation density. This suggests that a heterogeneous structure characterized by dislocation density, i.e., hard regions with high dislocation density (24 % in area) and soft regions with low dislocation density (76 % in area), was designed in the steel with a reduction of ∼20 %. This heterogeneity triggers additional strengthening and strain hardening mechanisms, thereby enhancing the strength-ductility synergy (yield strength: 1266 MPa, ultimate tensile strength: 1415 MPa, and fracture elongation: 29 %). This cold-rolling strain-induced heterostructure offers a promising and cost-effective avenue for the development of Fe-Mn-Al-C steels with superior strength-ductility balance.