Fatigue Enhancement of Ti-6Al-4V via Ex-situ Warm-Shot-Peening (WSP)

To explore the potential beneficial effect beyond shot peening (SP)’s conventional performance, ex-situ warm shot peening (WSP) of Ti-6Al-4V coupons have been carried out. The coupons were pre-heated to 200 and 400 °C, before they were immediately transferred into a SP booth for shot-peening. While high cycle fatigue (HCF) tests did not detect a favorable improvement in fatigue life at high (0.9F0.2) and medium loadings (0.7F0.2), a significant increase in cycle-to-failure (Nf) in low loading (0.5F0.2) was observed when the ex-situ WSP temperature was raised to 200 and further to 400 °C. Center hole drilling and electron backscatter diffraction (EBSD) were employed to unveil the mechanism for such fatigue improvement.