High-cycle bending fatigue behavior of TC6 titanium alloy subjected to laser shock peening assisted by cryogenic temperature

摘要

Aiming at the problem of high-cycle bending fatigue (HCBF) of aeroengine blades, the coupling strengthening process of laser shock peening assisted by cryogenic temperature was proposed. Transmission electron microscopy (TEM) and electron backscattered diffraction (EBSD) was employed to characterize the microstructures, while the in-deep residual stress was tested by the XRD technique. Moreover, the HCBF behavior of fatigue specimens were also compared. The experimental results showed that cryogenic laser shock peening (CLSP) induced a higher-density of dislocation and deformation twins. The surface compressive residual stress (CRS) of the CLSP specimen was increased by 13.3% than that of the room temperature laser shock peening (RT-LSP) specimen. Compared with the RT-LSP specimen, the damping ratio and fatigue life of CLSP specimen increased by 15.4% and 32.94%, respectively. The analysis results revealed that the higher-density of dislocation, deformation twins, and the high-amplitude CRS processed by CLSP can effectively suppress the initiation and propagation of HCBF cracks, thus significantly improving the HCBF life.