A Study of Impact Toughness Behavior and High Cycle Fatigue Properties of Al-Li 8090 Alloy Processed by Cryorolling and Post-Deformation Annealing

This study investigates the microstructural evolution and mechanical properties such as tensile, impact toughness, and high cycle fatigue (HCF) of cryorolled (CR) and post-rolled annealing treatment of Al-Li 8090 alloy. The solution-treated (ST) Al-Li 8090 alloy was cryorolled to a true strain value of 2.3 and annealed in the temperature range of 100 degrees C - 350 degrees C. The equiaxed microstructure in the ST samples is converted into ultrafine-grained (UFG) elongated microstructure along the rolling direction. The UFG microstructure, along with the high dislocation density in the CR specimen observed using electron backscattered diffraction, led to an increment in the tensile, hardness, impact toughness, and HCF properties such as the impact toughness and fatigue strength increased by 9.10% and 26.38%, respectively. The annealing temperature further enhances the mechanical properties up to 150 degrees C due to the evolution of strengthening precipitates such as Al2CuMg and Al3Ti, as well as the formation of recrystallized grains.