Dislocation configuration on the fatigue fracture behavior of a solution-treated 7005 aluminum alloy plate

In the present study, the dislocation configuration in 7005 aluminum alloy plate stored at room temperature for 96 h following solution quenching was changed by pre-stretch at room temperature for various deformations, to reveal its influence on the tensile properties, especially fatigue life and fatigue fracture characteristics of alloy plate. The results show that with the increase in pre-strain deformation to 16%, the thickness of the thin strip grains decreases from 7.70 to 6.31 μm, the dislocation density in the matrix of the plates gradually increases, especially the changing law of dislocation distribution inside a grain and among grains is "nonuniform-uniform-nonuniform". The plate exhibits an obvious hardening effect, the strength and hardness increase, but the elongation decreases monotonically. However, the fatigue performance of the alloy plates under the conditions of a maximum stress of 180 MPa and a stress ratio of R = 0 is improved by 3∼16% pre-strain deformation, the alloy plates underwent 12% pre-strain deformation have the longest fatigue life that is (1.10 ± 0.16) × 106 cycles, due to the higher dislocation density and the uniform dislocation distribution inside a grain and among grains, which is 169% longer than that of the alloy plates without pre-strain. The results provide an important theoretical basis and some experimental data for improving the fatigue performance of 7005 aluminum alloy plate used in high-speed railway and aviation industries.