Characteristics of laser welding-brazing joint of Al/Ti dissimilar alloys

Laser welding-brazing (LWB) of Ti-6A1-4V and 5056A1 was conducted using AlSi 12 filler metal. The microstructure characteristics of LWB Al/Ti joints were analyzed by SEM, EDS, XRD and optical microscopy. The joint strength was measured via tensile test. The results show that the joint has dual characteristics and can be divided into a welding part on the aluminium side and a brazing part on the titanium side. An intermetallic compound layer forms at the brazing interface between mixed seam metal and titanium. The intermetallic compound layer at interfacial top includes an acicular Ti-Al-Si intermetallic layer and a continuous Ti-Al intermetallic layer near titanium alloy. The intermetallic compound layer at interfacial bottom is thin and different from that at top. The average tensile strength of joints is 298. 5 MPa. Fracture is prone to occur in the seam metal nearby brazing interface.