Tensile Behavior of Intercritically Annealed Ultra‐Fine Grained 8% Mn Multi‐Phase Steel

The room temperature tensile behavior of intercritically annealed hot‐rolled Fe‐8%Mn‐0.4%C‐3%Al‐2%Si‐(0–0.2)%V steel, with an ultra‐fine grained austeno‐ferritic microstructure was investigated. An initial athermal martensite microstructure provided a high density of ferrite nucleation sites during intercritical annealing, resulting in an ultra‐fine grained microstructure. Carbon and manganese were partitioned to austenite during intercritical annealing. The austenite phase exhibited the plasticity‐enhancing TWIP + TRIP effect, i.e., deformation twinning and strain‐induced martensite transformation occurring in succession, which resulted in a superior work hardening rate. The intercritically annealed hot‐rolled Fe‐8%Mn‐0.4%C‐3%Al‐2%Si‐0.2%V steel exhibited a total elongation of 40%, a yield strength of 920 MPa, and tensile strength of 1200 MPa.