Laser beam welding of dissimilar aluminium alloys of 2000 and 7000 series: effect of post-welding thermal treatments on the T-joint strength

Two experimental aluminium alloys (belonging to 2000 and 7000 series respectively) were welded using the laser beam welding (LBW) technique and an Al–Si alloy as filler. Different combinations of pre- and post-welding thermal treatments were proposed. The change of strength during aging treatments was investigated by microhardness measurements carried out on the weld and on the regions of the alloys not affected by the LBW process. The microstructure of the welded specimens was studied by scanning electron microscopy and energy dispersive X-ray spectroscopy. The strength of the joints after different thermal treatments was checked by T pull tests. Different thermal treatments resulted in different final strengths of the joint.