Effects of laser peening with different coverage areas on fatigue crack growth properties of 6061-T6 aluminum alloy

The effects of coverage area on fatigue crack growth (FCG) properties of 6061-T6 aluminum alloy subject to multiple laser peening (LP) impacts were investigated. Residual stress, micro-structure and fatigue striation pattern on fracture cross-sections were analyzed. Compressive residual stresses and dense dislocation arrangements can be found in the superficial layer after LP. LP coverage area has a direct influence on FCG properties as verified by different size of shell ridges and fatigue striation spacing on fracture cross-sections. Meanwhile, FCG rate decreases with the increase of compressive residual stresses distribution perpendicular to the crack growth direction in the initial FCG stage.

► Effects of LP with different coverage areas on FCG properties were investigated.
► Effects of residual stress and micro-structure on FCG properties were analyzed.
► Crack arrest and fatigue striation pattern on fracture cross-sections were studied.
► The reduction of FCG rate by LP in initial and final FCG stage was analyzed.