Effect of pneumatic shot peening on the high and low cycle combined fatigue life of K403 turbine blades

摘要

The effect of pneumatic shot peening (PSP) on the fatigue properties of K403 turbine blades has been investigated under the high and low cycle combined fatigue (CCF) load with two types of turbine blades: untreated blades and PSP treated blades. It is found that there is a threshold vibration stress for the blades in this study. The PSP has a positive effect on the CCF life of blades mainly due to the compressive residual stress resulting in the reduction of the number of crack sources and propagation rate, when vibration stresses are below the threshold vibration stress. However, the PSP treatment has no effect or a negative effect when vibration stresses are above the threshold value. The compressive residual stress is released along with the microstructure changes of K403 alloy. Meanwhile, the microstructure changes, reflected in the precipitation of the lamellar MC carbides and σ phases, can accelerate the processes of crack initiation and propagation.