Friction welding of electron beam melted Ti-6Al-4V

Ti-6Al-4V samples produced by electron beam melting (EBM) are welded using solid-state friction welding (FW) process. The microstructure of the weld sample shows the presence of fine equiaxed alpha grains with irregular beta phase. Microstructural investigations reveal a pronounced change in the shape and size of the alpha phase in the weld metal as-compared to the base material along with the disappearance of columnar prior beta grains. Such variations in the microstructure significantly change the mechanical properties of the FW material. The hardness in the weld zone increases and a decrease of hardness is observed along the heat affected zone (HAZ) with respect to the base metal as expected. Similarly, the room temperature tensile tests show an improvement of ductility in the welded EBM samples. However, the yield and the ultimate strength show a marginal drop in the welded samples compared to the as-prepared EBM specimens. The present work demonstrates that solid-state FW process not only permits successful joining of additively manufactured materials, but also helps in improving their ductility.