Influence of laser power on microstructure and mechanical property of laser-welded Al/Cu dissimilar lap joints

Laser welding is used in joining 6061 aluminum and 110 copper. The effect of laser power on the microstructure and mechanical properties of Al/Cu lap joints are investigated by using of the optical microscopy (OM), scanning electron microscope (SEM), tensile test device and Vickers hardness device, respectively. The investigation results indicate that the weld metal (WM) mainly consists of the (Al) solid solution and the Al-Cu eutectic alloy, and the interface zone between the copper base metal (BM) and the WM mainly consists of the (Cu) solid solution, the Al2Cu IMC with the shape of serrated and the Al-Cu eutectic alloy with the shape of vermicular. The shear strength of Al/Cu joints first increases and then decreases with the increase of the laser power, maximum is about 99.8 MPa with the 2.45 kW laser power. The fracture surface mainly occurs in Al-Cu eutectic region with the characteristic of brittle fracture. The highest Vickers hardness of Al/Cu lap joints located at the interface zone.