Experimental study and fatigue life prediction on high cycle fatigue performance of laser-peened TC4 titanium alloy

摘要

Laser shock peening (LSP) is an innovative surface treatment, which has been successfully applied in aero-engine compressor blades to improve high cycle fatigue performance. Deep compressive residual stress layer with a gradient distribution can be produced, which is the special advantage of LSP and plays a main role in high cycle fatigue performance improvement. Therefore, compressive residual stress, and especially the gradient distribution feature should be simultaneously considered in high cycle fatigue life prediction for laser-peened component. In this work, firstly, TC4 titanium alloy, a typical material used for aero-engine compressor blade, was treated by LSP with different power densities, overlapping rates and shocks respectively. High cycle fatigue life of TC4 titanium alloy is enhanced from 1473 ×10~3 cycles to 6148 × 10~3 cycles, by 317% increase with LSP treatment. Compressive residual stresses with a gradient distribution induced by LSP were disposed into an equivalent parameter according to critical plane method. At last, high cycle fatigue life of laser-peened TC4 titanium alloy specimens was successfully predicted within twice-fold error band, comprehensively considering equivalent compressive residual stress and FINDLEY model.