Multi-mechanism crystal plasticity simulation and experimental study for uniaxial tensile deformation of 7Mn1Al Medium-Mn steel

The uniaxial tensile behavior and microstructure evolution of 7Mn1Al Medium-Mn steel were studied using mechanical testing, XRD, and quasi in-situ EBSD. A coupled crystal plasticity constitutive model incorporating dislocation slip, twinning, and phase transformation mechanisms was developed, and a finite element model based on pre-deformation EBSD data was constructed. And then the uniaxial tensile deformation process was simulated using ABAQUS. The 7Mn1Al steel, after warm rolling and annealing, achieved excellent properties with a tensile strength of 1089 MPa, elongation of 46 %, and PSE of 50 GPa·%. During deformation, austenite stability variation caused a two-stage TRIP effect. Stress and strain alternated between ferrite and martensite-austenite islands, driven by the TRIP effect, which enhanced the work-hardening rate of the MA islands. Martensitic transformation occurred primarily at ε < 0.2, starting in regions with <101> austenite orientation and granular morphology, suppressing twinning at later stages.