Effects of Specimen Thickness on Fatigue Crack Growth Behaviour of Titanium Alloys in Air and in 3%NaCl Solution
Masaki NAKAJIMA, Toshihiro SHIMIZU and Keiro TOKAJI
Abstract:Fatigue tests were conducted on a ƒÀ Ti-15Mo-5Zr-3Al alloy and a (ƒ¿+ƒÀ) Ti-6Al-4V alloy in air and in 3%NaCl solution to clarify the effects of specimen thickness and environment on fatigue crack propagation (FCP) behaviour. Specimens with three different thicknesses, I.e. 0.5, 2 and 10mm, were employed in the present study. In both environments, the FCP rates in Ti-15Mo-5Zr-3Al alloy were almost the same for all the thicknesses in high ƒ¢K region, but were enhanced in low ƒ¢K region with decreased thickness. On the other hand, in Ti-6Al-4V alloy, the da/dN-ƒ¢K relationships in air were similar for all the thicknesses, while in 3%NaCl solution, FCP rates were enhanced with decreased thickness in high and low ƒ¢K region. It was found that the FCP resistance of Ti-15Mo-5Zr-3Al alloy was inferior to that of Ti-6Al-4V alloy, except for high ƒ¢K region in 3%NaCl solution. Key Words:Fatigue, Corrosion fatigue, Crack growth behaviour, Specimen thickness, 3%NaCl solution, Titanium alloy, Ti-15Mo-5Zr-3Al, Ti-6Al-4V