Flash annealing yields a strong and ductile medium Mn steel with heterogeneous microstructure

Austenite reversion treatment (ART) is usually used to obtain retained austenite (RA) in medium Mn steel (MMS). In this contribution, we proposed a flash-annealing strategy to produce MMS, which allows us to efficiently obtain a large amount of RA in MMS via the "explosive" nucleation of austenite and the fast C partitioning. Furthermore, flash-annealing can also render a heterogeneous ferritic matrix consisting of recrystallized/non-recrystallized ferrite grains, leading to heterogeneous deformation-induced hardening. As compared to the conventional ART processed MMS, the unique heterogeneous microstructure in the flash-annealed MMS leads to a higher yield and ultimate tensile strength but a marginal ductility loss. Flash-annealing provides an alternative route to tailor microstructure and optimize the mechanical performance of steels. (c) 2021 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.