Effects of shot peening on improving high-temperature fretting fatigue performance of nickel-based single crystal superalloy tenon attachment

In order to reveal the shot peening (SP) strengthening mechanism on the high-temperature fretting fatigue performance of nickel-based single crystal (NBSC) tenon attachment, fretting fatigue tests under three load conditions were carried out at 600 ℃. The results showed that the fretting fatigue life of SP NBSC tenon attachment could be increased to 357.53 % of that of non-SP NBSC tenon attachment. SP changed the fretting fatigue crack initiation site from the contact surface to the subsurface. The larger the peak load was, the closer the crack initiation site was to the contact surface. SP changed the fretting fatigue crack propagation path, and the crack propagation deviated from the original direction approximately perpendicular to the contact surface. SP increased the microhardness by 28.1 %, induced −1098 MPa maximum compressive residual stress (CRS) and generated a mean geometrically necessary dislocation (GND) density of 7.55× 1014 m−2 near the surface. The micro convex bodies and greater microhardness alleviated the wear damage, and the increased dislocation density and CRS enhanced the inhibition of crack initiation and propagation, which were the strengthening mechanism of SP to improve the fretting fatigue performance of NBSC tenon. This work aimed to provide support for the long-life manufacturing of NBSC turbine blades.