Friction Stir Welding of High-Workability Titanium Alloy

摘要

Two mm thick Ti-6AI-4V alloy and SP-700 alloy plates were welded under various FSW conditions in order to investigate the microstructure and mechanical properties of the joint. When the welding was performed below the β-transus temperature, the stir zone consisted of the fully equiaxed primary α+β phase. On the other hand, when the welding was conducted above the p-transus temperature, a lamellar structure was observed in the stir zone. The tensile strength of the SP-700 joint welded above the β-transus temperature was higher than that of the T1-6AI-4V joint because of the finer lamellar structure. The lamellar structure increased the absorbed energy for fracture of the joint.