Shear-induced, solid-state joining of Ti-6Al-4V and Ti17 titanium alloys

The role of shear strain during the solid-state joining of Ti-6Al-4V and Ti17 sheet materials by symmetric and asymmetric rolling was established. The mechanisms of interface-zone formation involved a combination of intermixing and inter-diffusion. Quantified by EDX analysis and TEM imaging, the interface-zone thickness was directly dependent on the level of shear strain. Post-joining tension and lap-shear measurements followed the same tendency, while annealing led to an opposite effect. For annealed samples, the decrease in interface-zone thickness with shear prestrain and the concomitant loss of strength was rationalized on the basis of recovery and recrystallization during heat treatment and, therefore, the elimination of rapid-diffusion paths.