Beam oscillation, porosity formation and fatigue properties of electron beam welded Ti-6Al-4V alloy

Butt joints of Ti-6Al-4V plates were produced by electron beam welding process using both oscillating and non oscillating beams. The joints were then inspected using X-ray computed tomography technique for three-dimensional observation of porosities across the weld zone. Joints produced using beam oscillation were found to have contained well dispersed and significantly lower porosity content than the one made using non-oscillating beam. An optimum pore diameter of 312 pm has been identified below which the gas bubbles will be entrapped as pores under the used welding conditions. The corresponding strain-controlled fatigue tests demonstrated significantly higher fatigue life for oscillating beam joints than their non-oscillating beam counterpart.