Effect of surface integrity induced by shot peening on high-temperature fatigue property of K4169 alloy

Abstract

The surface roughness, residual stress and micro-hardness of K4169 alloy specimens were characterized by roughness tester, X-ray diffraction（XRD）stress tester and micro-hardness tester. The results indicate that median fatigue lives of the specimens increased by 10.2-43.9 times after SP treatments compared with untreated specimens. Furthermore, the number of fatigue source decreased to only one and the site of fatigue source transferred from the surface to the subsurface. The harden layer with the depth of 0.10-0.32 mm and the surface residual stress of −941-−1023 MPa are obtained. The depth of harden layer increased with the increasing of peening intensity. The grooves obtained from the grinding disappeared and the surface stress concentration intensity decreased largely after SP. The improvement of fatigue life is mainly ascribed to the enhancement of surface integrity induced by SP.

Keywords

• shot peening
• superalloy
• fatigue
• surface integrity