Explication of Microstructural Evolution and Mode of Recrystallization in Dissimilar Al6061-Ti6Al4V Friction Stir Welds

The present study elucidates the microstructural evolution and recrystallization mechanism of Ti-6Al-4V, and Al6061 dissimilar friction stir welded joints. The stacks of Ti layers near the Al-Ti interface were observed, later fragmented into fine particles under shoulder pressure. These particles were dispersed over the Al matrix due to the stirring action of the tool, thus providing composite strengthening at the stir zone (SZ). The electron back-scattered diffraction results revealed 91% and 77% of strain-free recrystallized grains at the Ti interface and SZ, respectively. Hence, both the base materials were dynamically recovered, but Al was subjected to continuous dynamic recrystallization while adiabatic shear bands' formation influenced Ti's recrystallization.

Automated summary

The study investigates the microstructural evolution and recrystallization mechanism of Ti-6Al-4V and Al6061 dissimilar friction stir welded joints. It is found that the Ti layers near the Al-Ti interface are initially stacked and later fragmented into fine particles under pressure. These particles are dispersed in the Al matrix by the stirring action of the tool, strengthening the stir zone. Recrystallization is observed in both base materials, with Al undergoing continuous dynamic recrystallization and Ti being influenced by adiabatic shear bands' formation.