Pulsed Nd: YAG laser dissimilar welding of Ti/Al3105 alloys

Overlapped strips of titanium grade 2 and aluminum 3105-O alloy were welded together by an innovative spot-like pulse laser procedure. The tactile seam tracking on ring paths yielded reliable weld fit-up of 1 and 0.5 mm thickness strips. Since the welding parameters of Ti-Al were narrow, three welding speeds of 4, 5 and 6.67 mm•s-1 were chosen for the pretest conditions. The microstructural investigations showed that intermetallic compound Ti3Al, formed in Ti-rich fusion zone. Cracks formed in the Al-rich fusion zone as a result of TiAl3 precipitation. Dimple fracture occurred at 6.67 mm•s-1 welding speed. Longer mixing time at Ti-Al interface occurred at lower welding speeds of 4 and 5 mm•s-1, which led to the formation of thicker intermetallic compounds and more massive crack generation. It also increases the hardness of the fusion zone and results in brittle fracture type during the tensile test. The highest strength was achieved with a welding speed of 4 mm•s-1 which was a result of more massive weld nugget and lower porosity.