Fatigue Crack Growth Rate Characteristics of Laser Shock Peened Ti-6Al-4V

Abstract

The fatigue crack growth rate (FCGR) characteristics of Laser Shock Peened (LSP) titanium 6Al-4V were examined and compared to those of unprocessed material. The FCGR resistance of LSP processed material tested at low stress ratios (R) is shown to be significantly greater than for unprocessed, baseline material. The increased damage tolerance can be attributed to the large residual compressive stresses generated by the LSP process. Differences in the growth rate behavior due to LSP can be accounted for by using the closure corrected effective stress intensity range, ΔKeff, which takes into account only the portion of loading above the crack opening load. The rationale of using ΔKeff is also demonstrated through fractographic investigations.