Effects of laser peening on residual stresses and fatigue crack growth properties of Ti-6Al-4V titanium alloy

The effects of laser peening (LP) with different laser peening coverage rates on residual stresses and fatigue crack growth (FCG) properties of Ti-6Al-4V titanium alloy were investigated. Residual stresses after LP and micro-structure with different fatigue striation patterns on fracture cross-sections were analyzed. Compressive residual stresses and dense dislocation arrangements can be obtained in the superficial layer after LP. The influence of compressive residual stresses induced under different LP coverage rates on FCG properties was revealed. LP coverage rate had an apparent influence on FCG properties as confirmed by the fatigue striation spacing on fracture cross-sections. Moreover, FCG rate decreased with the increase of compressive residual stresses perpendicular to the crack growth direction, which indicated that LP had an obvious inhibitory effects on FCG.