Simultaneously enhanced strength, ductility and formability of Al-Mg-Si-Cu-Zn-Fe-Mn alloy sheets by coupling distribution of solute, phases and grains

Enhancing comprehensive mechanical performance including high strength, high ductility and excellent formability are prior demands for applications of Al-Mg-Si-Cu alloys. The results of this study reveal that an optimized microstructure with reasonable coupling distribution of solute and phases can facilitate the grain refinement and formation of random textures. Achieving higher average plastic strain ratio (r = 0.6994) and lower planar anisotropy (Delta r = 0.053) improves the formability of the Al-Mg-Si-Cu-Zn-Fe-Mn alloy sheets. As the variation of distribution of solute, phases and grains in the pre-aged alloy sheets, the ultimate tensile strength increased from 300 +/- 3 MPa to 334 +/- 5 MPa and the elongation increased from 23.1% to 28.2% both in the rolling direction due to the enhancement of strain hardening rates and delaying the formation of necking during plastic deformation. The evolution of microstructure formed coupling distribution of solute, phases and grains, and related mechanisms of high strength, ductility and formability have been discussed in a detailed way. This study provides valuable insights into the coupling distribution design and control of solute, phases and grains, and its effect on the mechanical properties and deformation behavior of Al alloys.