Effect of pneumatic shot peening on the high and low cycle combined
fatigue life of K403 turbine blades
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 blades: untreated blades
and PSP treated blades. It is found that there is a threshold vibration
stress which should be 194MPa. 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 or negative effect when vibration
stresses are above the threshold value. The compressive residual stress
is released along with the microstructure changes of K403. Meanwhile,
the microstructure changes, reflected in the precipitation of the
lamellar MC carbides and σ phases, can accelerate the process of crack
initiation and propagation.