Effect of final rolling reduction on the microstructure and mechanical properties of Mg-Gd-Y-Zn-Zr alloy sheets

The Mg-8.2Gd-3.8Y-1.0Zn-0.4Zr (wt.%) alloy was hot rolled with different final rolling reductions at 400 °C. The microstructure evolution and texture of the sheets were analyzed, and their effect on the mechanical properties was discussed. All of the rolled sheets consist of fine dynamically recrystallized grains with almost random orientation, large deformed grains with strong basal texture. In addition, bent lamellar-shaped long period stacking ordered (LPSO) phases due to kink deformation were observed in the deformed grains. The volume fraction of the dynamic recrystallization increased with increasing final rolling reduction and the basal texture weakened gradually. The strength of the alloy sheets changed a little with increasing final rolling reduction, while the yield anisotropy and the ductility were significantly improved. The sheet final-rolled with thickness reduction of 60% exhibits tensile yield strength of 306. MPa, ultimate tensile strength of 393. MPa and elongation to failure of 14.6% at ambient temperature, and tensile yield strength of 264. MPa, ultimate tensile strength of 345. MPa and elongation to failure of 19.4% at 250 °C.