Original Article

Tailoring mechanical properties of a hot-rolled Fe-Mn-Al-C-Cr-V steel via reversed austenite transformation

Department of Materials Physics and Chemistry, School of Materials Science and Engineering, and Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang, 110819, PR China

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Received: 15 December 2025
Accepted: 26 April 2026

Abstract

An Fe-0.3C-5Mn-2Al-0.8Cr-0.15V steel was processed by austenite reversed transformation (ART) in the intercritical range of 650–750 °C to tailor its microstructure and mechanical behavior. Thermodynamic calculation and dilatometry guided the ART schedule, and the resulting microstructures were characterized by scanning electron microscopy (SEM), electron backscatter diffraction (EBSD) and X-ray diffraction (XRD), combined with room-temperature tensile testing and fracture analysis. Intercritical annealing promotes a transition from a tempered-martensite matrix with scarce retained austenite (RA) at 650 °C to a ferrite+RA duplex structure with banded RA at 700 °C, and finally to coarse lath ferrite with reduced, unstable RA at 750 °C. The 700 °C treatments provide the best strength–ductility synergy through transformation induced plasticity (TRIP)-assisted, Portevin Le Châtelier (PLC)-affected work hardening, whereas 650 °C and 750 °C lead to high-strength but low-ductility states. The results highlight ART-controlled RA fraction, morphology and stability as key levers for designing lightweight medium-Mn automotive steels.