Dissimilar joining of aluminum to titanium is problematic due to the large difference in melting point of the twometals and the formation of potentially brittle intermetallic phase on the weld interface. High power ultrasonicspot welding is a low energy input solid-state welding technology that has potential capacity to solve this problem.In this study, AA6111 aluminium alloy and TiAl6V4 titanium alloy were successfully welded by high powerultrasonic spot welding using two different types of welding tips, a rectangular tip and a round tip. Lap shearstrength testing and high resolution three-dimensional laser surface profile scanning were applied to examine weldgeometry and weld mechanical performance. The effects of welding time on peak load and fracture energy wereinvestigated. The weld interface microstructure was investigated using scanning electron microscopy andtransmission electron microscopy. The joints welded by the round tip has a shallower and smoother footprint,larger welded area and a longer fracture path than the rectangular tip, which result in higher lap shear strength andfracture energy.
展开▼
