Mechanical Properties of Thick Section Titanium 6A1-4V Friction Stir and Electron Beam Welds

摘要

In this study, Friction Stir Welding was developed in 25 mm thick Ti-6A1-4V alloy plate. The microstructure and mechanical properties of these thick section Friction Stir Welds were evaluated and compared to Electron Beam Welds produced in the same thickness material. It was found that the solid state Friction Stir Welds resulted in a coarse grained transformed beta microstructure with large alpha platelet colonies and grain boundary alpha as a result of super transus processing temperatures and slow cooling rates. This microstructure led to lower strengths, but improved ductility compared to both the Electron Beam Welds and Base Metal. The rapidly solidified structure of the Electron Beam Weld nugget resulted in relatively coarse prior beta grains, but with a much finer acicular alpha structure within the prior beta grain boundaries. The Electron Beam welds possessed higher strength, but reduced ductility compared to the base material.