Microstructural evolution, tensile property and dynamic compressive property of FSWed Ti–6Al–4V alloy

Friction stir welding was applied to Ti–6Al–4V plates with 5 mm in thickness. The microstructure and mechanical properties were investigated. A full lamellar microstructure was developed near the top surface, and the size of prior β grain gradually decreases as the distance from the top surface increases. The microstructure of the bottom is fine equiaxed α grains, and the mean size is 2 μm. A mixture microstructure consisting of primary α, lamellar α + β and fine equiaxed α is discovered in thermomechanically affected zone (TMAZ). Results of transverse tensile test show that the tensile strength of the joint reaches 98% that of the base material (BM). Quasi-static compression test shows that the joint exhibits larger compressive strength and failure strain than the BM. Dynamic compressive strength of the joint is close to that of the BM; furthermore, the strain at the peak stress and energy absorption of the joint are larger than those of the BM.