Effect of repeated impacts on mechanical properties and fatigue fracture morphologies of 6061-T6 aluminum subject to laser peening

► Nano-hardness and fatigue lives after multiple LP impacts were analyzed. ► Micro-morphologies of fatigue fracture were quantitatively investigated. ► Distance from FCI to top surface increased with the increase of LP impact number. ► FSS of FCG region increased with the increase of LP impact number. ► Enhancement mechanism of LP on the resistance of FCI and FCG were revealed.