Effect of Plastic Deformation on the Microstructure and Mechanical Properties of an Al-Li-Cu-Mg Alloy after Aging

The influence of the hot and cold plastic deformations through rolling, as an example, on the strength properties and ductility, as well as the microstructure, has been analyzed in Al-4.3Cu-0.95Mg-0.8Li (wt.%) alloy after artificial aging. A combination of hot (before quenching) and cold (before aging) deformations using longitudinal-transverse rolling schemes was shown to provide a high level of strength properties and a low degree of their anisotropy in the studied alloy after aging at 170°C for 12 hours. Therefore, the yield stress σ0.2, tensile strength σB, and elongation-to-fracture δ reached 470 ± 2 / 465 ± 3 MPa, 506 ± 3 / 505 ± 3 MPa, and 5.7 ± 0.4 / 5.9 ± 0.9% in orthogonal test directions. Microstructure analysis showed that dynamic and static recrystallization occur predominantly during hot deformation by rolling and heating between reductions, respectively. Following heating for solution heat treatment did not significantly change the grain structure compared to the alloy immediately after hot deformation. After cold deformation and aging, the sizes of strengthening particles of various phases decrease, and the {111}Al T1 (Al2CuLi) plate precipitation is additionally intensified in the studied alloy compared to that after hot deformation, solution heat treatment, and aging. Control of the grain structure of the studied alloy during hot deformation, optimal distribution and high density of dislocations formed during cold deformation, and particles with a preferred orientation after artificial aging make it possible to achieve a balance of strength and plasticity properties in different test directions.