Shear Induced Solid-State Joining of Dissimilar Titanium Alloys
Technical Report,12 May 2016,11 May 2018
DEAKIN UNIVERSITY Burwood Australia
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Solid-state joining of dissimilar titanium alloys could be applied for many aerospace applications. Joining of dissimilar alloys during manufacturing, in particular asymmetric rolling AR, is suggested for panel-to-panel construction. 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 pre-strain 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. This work provided insight into the mechanisms of bond formation under conditions of large shear and high hydrostatic pressure. It shows that the concurrent asymmetric rolling of dissimilar titanium alloys with simultaneous nanostructuring of interface layer produced the high integrity bond and opens an avenue for production the bimetalic titanium sheets with enhanced mechanical properties.