The effect of the adhesive on the microcracks in the laser welded bonding Mg to Al joint

The fracture of the laser welded bonding (LWB) Mg to Al alloy joint was analyzed. In order to find the cracks source, the microcracks in LWB fusion zone were observed by scanning electron microscopy (SEM), comparing with that in the laser welding joint. The formation of the microcracks in LWB Mg to Al joint was discussed simply. The addition of the adhesive reduced the temperature contrast between the Mg-Al eutectic phase and the intermetallics. Thus, the stress concentration at the interface between the Mg-Al eutectic phase and the intermetallics was released. With the effect of the adhesion, the tensile shear test specimen of LWB joint was failed at the edge of the joint, the property of which was better than that of laser welding and adhesive bonding.