Investigation into effects of re-shot-peening on fretting fatigue behavior of Ti-6Al-4V

The effects of re-shot-peening treatment on fretting fatigue life/strength and the recovery of residual stress of the initially shot-peened Ti-6Al-4V were investigated at room and elevated temperatures. After subjecting to fretting fatigue up to about 40% of the total expected life of the initially shot-peened Ti-6Al-4V or to thermal exposure to 370 °C only, residual stress relaxed in the range of 20-50% of its value before fretting fatigue. The magnitude of stress relaxation depended upon the applied load level and test temperature. Re-shot-peening successfully recovered the relaxed residual stress up to the same level as obtained after the initial shot-peening. Further, fretting fatigue life after re-shot-peening, excluding pre-re-shot-peening fatigue life, was very close to that of the initially shot-peened specimen at a given stress level and test temperature. It thus appears that re-shot-peening nullified the effect of fretting fatigue damage after the initial shot-peening.