抄録
When Ti-6Al-4V alloy was polished by using diamond paste or #400 emery paper, fatigue cracks initiated at the surface and its fatigue strength scattered widely. It was considered that the scatter of fatigue strength depended on the local surface morphology. On the other hand, when the fatigue crack initiated at the subsurface with shot-peening, the scatter of fatigue strength became narrowed remarkably. The fatigue strength of the shot-peened specimen, however, decreased again in the long-life region, and no fatigue limit was recognized even more than 107 cycles. This phenomenon might depend on the residual stress distribution.
