Effects of texture and mechanical anisotropy on the superplastic behavior in warm-rolled Fe–10Mn–4Al–1.5Si–0.3C medium Mn steel

This study investigates the mechanical anisotropy and superplastic behavior of warm-rolled Fe–10Mn–4Al–1.5Si–0.3C steel, emphasizing the relationship between texture evolution and deformation-induced ferrite transformation. Experimental results reveal exceptional superplasticity in the rolling direction (RD), with a maximum elongation of 1564 %, significantly exceeding that of hot-rolled and cold-rolled medium Mn steels. The transverse direction (TD) and diagonal direction (DD) samples exhibited elongations of 620 % and 1060 %, respectively. The observed mechanical anisotropy is primarily attributed to texture evolution and dynamic ferrite transformation (γ→α). The RD sample exhibited a strong FCC Cube texture after warm rolling, which facilitated deformation-induced ferrite transformation during superplastic deformation. This transformation refined the microstructure and enhanced grain boundary sliding (GBS), leading to superior elongation. In contrast, the TD sample retained a dominant Brass rolling texture of FCC phase, which limited ferrite transformation and reduced superplasticity. Strain rate sensitivity (m) analysis at 800 °C confirmed GBS as the primary deformation mechanism, with the RD sample showing the highest m value of 0.72, correlating with its superior elongation. Further, dynamic grain co-rotation maintained the Kurdjumov–Sachs orientation relationship between deformation-induced α-ferrite and parent γ-austenite grains, facilitating GBS and uniform deformation. This study highlights the critical role of optimizing initial texture and phase transformation behavior in enhancing the superplasticity of warm-rolled medium Mn steels, providing valuable insights for improving superplastic forming processes.