A fatigue assessment of dissimilar titanium alloy diffusion bonds

Diffusion bonds between the dissimilar titanium alloy pairing Ti 6/4 and Ti 550 were produced from laboratory scale plate stock materials. Metallographic sections, chemical composition and micro-hardness traverses across the bond line are all presented as evidence of the form and integrity of these joints. The mechanical performance of the bonds was assessed under both monotonic tensile and low cycle fatigue loading utilising specimens which contained bonds orientated either perpendicular or inclined to the principal stress axis. In general, near Ti 6/4 parent properties were measured under both loading conditions. However, performance was occasionally influenced by the presence of bond line defects, particularly under fatigue loading.