Comparison of Surface Integrity and Fatigue Performance on TC17 Titanium Alloy After Shot Peening and Re-Shot Peening

In this study, we have systematically investigated how both shot peening (SP) and re-shot peening (RSP) affect the surface integrity and fatigue performance of TC17 titanium alloy. Surface integrity involves a competitive mechanism with the coexistence of beneficial and detrimental factors, both of which collectively determine the fatigue performance. While compressive residual stress (CRS), dislocation multiplication, and work hardening serve as beneficial factors, surface roughness and surface damage act as the detrimental factors. The results reveal high-intensity SP produced a deeper work-hardened layer. However, it also caused larger surface roughness and more severe surface damage, yielding the relaxation of the surface CRS and poorer improvement of the fatigue performance than that achieved with medium-intensity peening. The RSP treatment demonstrated a superior balance of surface integrity factors by effectively reducing the degree of surface damage and elevating the magnitude of surface CRS. Thus, a 45.9-fold improvement in fatigue life was achieved relative to the base material (BM) specimen. Surface CRS was identified as the primary factor contributing to the enhanced fatigue performance.