Effect of electron beam welding on microstructure and mechanical properties of Ti-6Al-4V alloy

Influence of electron beam welding (EBW) on 7 mm thick mill annealed Ti-6Al-4V alloy is studied in present work. Optimized EBW parameter such as accelerating voltage, beam current and welding speed was selected by conducting trials with the objective of full depth penetration of weld. Mechanical properties, microstructure, phase composition and weld bead geometry was studied. From the results it is found out that microstructure of the base metal is composed of slightly elongated α phase and transformed β phase. Dispersed acicular martensite α' phase is observed in fusion zone. The microstructure in heat affected zone which is divided into two parts: (1) fine grain zone (2) coarse grain zone, have difference in microstructure. The microhardness values of fusion zone are higher than heat affected zone and base metal. Weld strength was checked it was observed that its U.T.S and Y.S is on higher side that Joint and base metal sample but the % elongation is lower as compared to other samples. For all samples, weld width increase with increase in heat input, and have higher strength to those samples having maximum width.