Peculiar effects of inert gases on fatigue crack growth in an (α+β)-titanium alloy

It was unexpectedly found in previous studies that inert gas environments enhance fatigue crack growth in pure titanium. To investigate the mechanism of this peculiar effect, fatigue crack growth tests were performed on β-titanium, (α+β)-titanium and 7075 aluminum alloys in several inert gas environments. Fatigue crack growth rates were compared with those in vacuum. Increased fatigue crack growth rate was obtained only in the (α+β)-titanium alloy. Combined with the fact obtained in the previous studies, α-phase of titanium is considered to be sensitive to inert gases.