Laser welding of dissimilar aluminium alloys with filler material

Laser welding of dissimilar aluminium alloys with filler material Luís Filipe Amaro Pinto Instituto Superior Técnico – Technical University of Lisbon – Portugal September 2008 Abstract The aluminium alloys are materials with great potential because of its high strength and low weight. However, the welding of dissimilar aluminium alloys is difficult in autogeneous welding, due to these alloys are welding with filler material. The present work focus on welding dissimilar 6xxx series, and 5xxx with 6xxx series (the main components of these alloys are Al, Mg and Si), with filler wire. These alloys have particular application in the aerospace, military and information technology industries. A Nd:YAG laser, with a maximum pulsed power in PW mode of 5 kW was used to perform the welds. Fillers wires 4047, 4047A, 4043 and 5356 were tested for the different combinations of base materials. This research aimed at the selection of the filler wire that presents better performance in welding dissimilar Al alloys. The quality of welds was tested by macro graphic and microstructure analysis. Scanning electron microscope and hardness tests were also performed. The results indicate that with filler wires with compositions with low magnesium and high silicon contents it is easier to achieve good quality welds though attention needs to be payed to the required mechanical to assure the adequate service performance of the part. For the base materials studied, it is possible to conclude that the filler wire 4047 presented the best results in welding of dissimilar aluminium alloys series 6xxx and 5xxx. Key-Words Laser welding; Pulsed Nd:YAG Laser; Filler wire; Dissimilar aluminium alloys; Al 5xxx; Al 6xxx