Abstract
In this study, we investigated initiation and propagation behavior of small fatigue crack on A7075 and Ti-6Al-4V in vacuum environment. As well as the ambient air environment, so-called small fatigue crack behavior were observed in vacuum. In both materials, the fatigue crack initiation life and failure life in vacuum environment are always longer than that of ambient air environment. In case of A7075, effect of the air on small fatigue crack propagation rate is less than that of obtained on Ti-6Al-4V.
