“Soft-hard” microstructure evolution and its relevance to high strength–plasticity and low plastic anisotropy of Al–Mg alloys based on ultra-fast heating

Abstract

The mechanical anisotropy caused by the apparent texture after large plastic deformation and deformation strengthening in metals has always been a contradiction. Here, 80 % cold-rolled Al–Mg alloy was annealed using the ultra-fast heating process (500 °C/s heating to 450 °C), leading to substructured grains with high geometrically necessary dislocations (4.12 × 1014 m−2) and recrystallized grains with low geometrically necessary dislocations (0.78 × 1014 m−2); each of these accounted for approximately 50 % of the grains. The alloy's strength was much higher than the corresponding conventional annealing one, while the ductility remained unchanged. In addition, the weaker transition texture components such as Brass, Z, R-GossND, and Goss increased significantly due to the presence of many substructural grains. In contrast, the Cube texture decreased significantly, thus leading to a decrease in the texture intensity and, in turn, a significant reduction in the anisotropy. The excellent comprehensive properties are attributed to the microstructures with a mixture of “soft-hard” grains and multicomponent-low-intensity textures. The present study provides a new approach to fabricating Al–Mg alloys with high strength, high ductility, and a low anisotropy of the mechanical properties.