Numerical Prediction of the Effect of Laser Shock Peening on Residual Stress and Fatigue Life of Ti-6Al-4V Titanium Alloy

Abstract

Laser shock peening (LSP) is a promising surface strengthening technology to improve the fatigue life of alloy components. In this work, the residual stress field of Ti-6Al-4V titanium alloy induced by LSP was simulated based on finite element method (FEM), and then the fatigue lives of the non-LSP and LSP-treated specimens subjected to four-point bending were predicted using the software Fe-safe. The simulation results were compared and validated with the corresponding experimental results. LSP treatment produces a maximum compressive residual stress (CRS) of up to 800 MPa on the surface of the specimen and a CRS layer with a thickness of 0.623 mm under the upper surface of the specimen. The existence of the CRS layer reduces the maximum principal stress from 608 MPa to 540 MPa and changes its location from the upper surface into the internal position at a depth of about 0.6 mm during the four-point bending process. This results in experimental and predicted fatigue lives 4.2 and 17.24 times longer for the specimens with LSP pretreatment compared to those without LSP.

Keywords

• laser shock peening
• fatigue life
• four-point bend
• compressive residual stress
• numerical prediction