Fatigue behavior of Ti-17 titanium alloy subjected to different laser shock peened regions and its microstructural response

Laser shock peening (LSP) induced compressive residual stress plays a significant role in improving the fatigue performance of metallic components, while the synchronously generated plastic deformation may influence reversely. In this study, the effects of different peened regions on the fatigue behavior of Ti-17 titanium alloy were investigated. The fatigue life increased with peened region tangent to the edge and decreased when peening entirely covered the edge. Finite element modeling showed a minor difference in the residual stress distribution but a distinct difference in the local plastic deformation. Direct peening covering the edge introduced a detrimental collapse to the edge, which accounted for fatigue life reduction. Additionally, the microstructural responses including XRD, EBSD and TEM observations were analyzed, and quantitative dislocation densities were further calculated.