Effect of EBW Parameters on Weldment Quality of Ti6Al4V Alloy

The penetration characteristics of EBW are primarily dependent on the main beam current (Iw), potential difference between the cathode and anode (voltage, V) and the welding speed (S). There are other influencing parameters like weld focus current (If), welding gun to work distance (GW) and beam oscillation.In the present study, the effect of work distance on focus current and on penetration of Ti6Al4V weld is studied using a 60kV, 30kW EB welding machine. Weld focus current is measured over a range of work distance and variation in its pattern is studied. Similarly, the variation of depth of penetration by varying the work distance and varying the focus current at a particular work distance constant are also analyzed.It is observed that, focus current is inversely proportional to the work distance and the variation in focus current per unit change of work distance is high in the shorter work distance region. The change in focus current and work distance affects the weld penetration and fusion zone geometry. For optimum penetration at a given work distance, the beam focus should be below the surface in keyhole welding. As the work distance increases, the penetration capacity of the beam decreases and maximum penetration is obtained in lesser work distance region.