Effects of scanning path gradient on the residual stress distribution and fatigue life of AA2024-T351 aluminium alloy induced by LSP

摘要

Laser shock peening (LSP) is a superficial treatment process employed to induce beneficial residual stress to retard fatigue crack growth, resist corrosion and wear and enhance the mechanical properties of metals. This research study the effects of scanning path gradient on the residual stress and fatigue life of AA2024-T351 aluminum alloy induced by LSP using experiment and 3D FE simulation to optimize the scanning path gradient. The material under study is of great importance in the aerospace industry on fuselage and lugs. Two divergent strategies were used, the scanning path gradient (strategy 1) and the scanning path in advancing direction (strategy 2) both on double-sided dog-bone specimen, and their residual stresses and fatigue life was compared. After LSP, both the LSP treated specimens residual stress and fatigue life were improved. The results showed that the fatigue life of the scanning path gradient was improved by 69.3% while that of the scanning path in advancing direction was improved by 93.5%. In addition, the magnitude of the residual stress on the apex surface was observed to be higher than the bottom surface. Results of the scanning path gradient for the residual stress was calculated by the 3D FE method and it was found to be in good agreement with the experiment results. We observed the presence of tensile residual stresses in between the apex and bottom surfaces after LSP.