Microstructure evolution of annealed 7075 aluminum alloy and its influence on room-temperature plasticity
Lin Hua, Xuan Hu, Xinghui Han
Abstract
Compared to hot forming, cold forming can manufacture components with higher accuracy and better mechanical properties. However, for some light-weight and high-strength materials, such as 7xxx series aluminum alloy, their room-temperature plasticity is poor, which limits the production of complex structural components of these materials. In this study, the microstructure evolution of annealed 7075 aluminum alloy and its influence on room-temperature plasticity were investigated. Firstly, the annealing experiments with different annealing temperature and soaking time were conducted, and the annealed microstructure evolution was analyzed. Secondly, the room-temperature tensile tests were conducted to evaluate the room-temperature plasticity. The relationship between annealed microstructure and plastic deformation behavior was studied. The new effect mechanisms of annealed microstructure on room-temperature plasticity was found. The results indicated that the annealed grains with high Schmid factor (˃0.4) adjacent to coarse granular-shaped secondary particles exhibited easy multiple slip system activation and smoothly transformed strain through the slip bands, which promoted the grain fragmentation. Concurrently, the secondary particles underwent rupture and separation. Owing to the low strain localization and multiple slip systems of the grain fragments, they can coordinately deform around the prior particle-matrix interfaces or between the separate particle pieces, which led to good room-temperature plasticity.