Microstructure-Superplastic Properties Relationship and Deformation Mechanism in a Novel Dual-Phase Medium Mn Steel: The Effect of Microstructure Anisotropy and Texture

In this paper, the tensile properties, texture evolution, and deformation anisotropy of a cold-rolled Fe−0.3C–6.86Mn–3.5Al steel during superplastic deformation at 650 °C–750 °C and 0.25 × 10⁻³ s⁻¹− 4 × 10⁻³ s⁻¹ were studied. In particular, under 750 °C and 1 × 10⁻³ s⁻¹, the anisotropic microstructure evolution and texture characteristics were measured using EBSD. The results indicate that Medium Mn steel (MMS) sheets exhibit significant anisotropy under high tensile stress. The transverse direction (TD) specimens exhibit the highest peak strength of 145 MPa, and rolling direction (RD) specimens exhibit the highest elongation of 1295 pct. The plastic anisotropy r value of the RD sample varied more significantly than that of the TD sample. When the RD sample fractures, the aspect ratio reaches its minimum value (1.52), and ellipse fitting angle (θ) distributes from 0 to 90 degree and from 180 to 90 degree, which indicates that a large number of grains have undergone rotation.