Influence of beam oscillation in electron beam welding of Ti-6AL-4V

Effect of beam oscillation on the evolution of microstructure and its correlation to mechanical properties for butt-welded Ti-6Al-4V plates has been studied using electron beam welding. Joints made with oscillating beam demonstrated higher ductility (by 10 to 15%) and notch toughness (by 20 to 30%) compared to those produced by non-oscillating beam. Evolution of such improved mechanical properties with beam oscillation has been corroborated with more uniform and fine microstructure, which has been attributed to the intense heat mixing, reduced temperature gradient, and more uniform cooling in the weld track. Narrow heat-affected zone and fusion zone with considerably reduced undercut depth were also obtained for oscillating beam joints. Interestingly, residual stress was found to be more in welds prepared with beam oscillation than its non-oscillating counterparts, although the magnitude of such stress irrespective of the welding condition was found to be much lower than those reported for arc welding.