Bending behavior, and evolution of texture and microstructure during differential speed warm rolling of AZ31B magnesium alloys

Differential speed warm rolling (DSR) at 473 K (200 °C) was carried out on AZ31B magnesium alloys. Bending curvature and the change in texture and microstructure caused by deformation asymmetry were experimentally investigated and compared with model predictions. Modeling of the DSR process was carried out using a finite-element approach incorporating the constitutive equation of AZ31B alloys. The variation in shear strain, velocity gradient and motion of neutral points was examined along with the differential velocity ratio (VR). The bending curvatures dynamically depended on the ratio of the roll velocity, reduction in area, and friction and heat transfer coefficients. The predicted texture was computed using a viscoplastic self-consistent model and was compared with experimental results. Texturing during DSR was dependent on both roll VR and bending curvature. The VRs producing negative and small positive curvatures were not effective in reducing the formation of basal fiber. Basal intensities decreased with positive curvature values. At a given temperature and rolling conditions, peak spreading along the rolling direction and peak broadening along the transverse direction of basal poles, {0 0 0 2}//ND, were observed. Shear bands, tensile and double twins, which contributed to texture weakening, were all detected in electron backscatter diffraction maps.