Effect of Laser Shock Peening on Fatigue Life of Full Scale Turbine Blades

Laser shock peening (LSP) is a promising surface treatment method for improving fatigue properties of turbine blades. The effect of LSP on combined low and high cycle fatigue (CCF) life of full scale turbine blade was investigated. The LSP is performed by YLSS-40 LSP equipment and the laser power density is 5.8 GW/cm². Thirteen LSP treated turbine blades and thirteen untreated turbine blades were selected to carry out the contrast test at high temperature in a bench environment. Experimental results show that there exists a critical vibration stress of blades, below which the CCF life was significantly prolonged by LSP, and above which the LSP has no effect or an adverse effect on the CCF life. The safe life of blades can be significantly increased after treated by LSP when the total stress is below the yield stress. However, the situation is a bit different when the total stress is above the yield stress. Although the safe life of LSP blades is longer than that of untreated blades in this situation, but the median life of blades is decreased after treated by LSP. The effect of LSP on the scatter in life plays a greater role in improving the safe life that directly leads to the safe life of LSP blades longer than the safe life of untreated blades when the total stress is above the yield stress.