Comparison of microstructure and mechanical performance of laser and electron beam welded Ti6Al4V alloy

Abstract

Laser beam welding and electron beam welding are the most recent joining technologies that interface engineering and physics concepts. The present research work focuses on the comparison of the microstructural and mechanical performances of Ti6Al4V, an alloy that displays sensible weldability owing to high susceptibility to oxidation process at elevated temperature, welded joints by using laser and electron beam welding. The as-welded alloy has been examined to study the effect of similar heat input conditions and focal point positions on butt-joint Ti6Al4V specimens in response of the weld morphology, microstructural feature, micro-hardness distribution and angular deformation. The results indicated that electron beam welding process is more appropriate and favorable to join Ti6Al4V alloy specimens and full penetrated electron beam weld joint is procured without any defects. However, narrow weld seam with refined grain structures is developed in the weld zone of laser beam welded specimens. Also, defocusing the beam position by − 1 mm contributed to grain refinement in the weld zone of laser and electron beam welded specimens. Moreover, the magnitude of micro-hardness distribution in the weld zone of laser beam weldments is higher than electron beam weldments by 0.66 times. However, the micro-hardness magnitude is substantially enhanced by 32% and 16% for laser and electron beam weldments, respectively, due to negative defocusing beam position. From the results, it is determined that the magnitude of angular deflection is higher for laser beam weldments than electron beam weldments due to higher difference in fusion zone areas across the neutral axis. Moreover, angular deflection magnitude in electron and laser beam weldments is lowered by 15.8% and 7.4%, respectively, due to negative defocusing beam position.