Fatigue crack growth in residual stress fields of laser shock peened Ti6Al4V titanium alloy

Abstract This study investigates fatigue crack growth behavior in residual stress fields induced by laser shock peening (LSP) and its effect on the fatigue life of Ti6Al4V titanium alloy. The two-dimensional residual stress distribution on the specimen surface prior to and post to fatigue crack growth tests was measured by X-ray diffraction. Laser peening with square spot and circular spot was performed on the fatigue specimens. The fatigue lives of LSPed specimens with square spot and circular spot were 1.68 and 2.38 times those of the unpeened specimens, respectively. The result showed that significant crack retardation was observed in specimens only at high compressive residual stresses levels, which was attributed to the reduction of local stress. The superposition principle combined with the weight function method was used to predict the fatigue crack growth rate in residual stress fields.