Impact of Al-Cu IMCs Thickness on Mechanical Properties in 6061 Aluminum/TU1 Copper Laser-Welded Joints

The thickness of the Al-Cu IMCs layer plays an important role in the mechanical properties of the aluminum/copper overlap joint by laser beam welding. In this work, the relationship among “the laser power—the thickness of the Al-Cu IMCs layer—the mechanical properties of welded joints” is tried to be established. Laser lap welding experiments were performed on aluminum/copper dissimilar metals under various laser power settings. And the weld seam formation, microstructure, mechanical properties, and Al-Cu IMCs layer thickness were measured and characterized. Finally, the relationship among “the laser power—the thickness of the Al-Cu IMCs layer—the mechanical properties of welded joints” was established. The results suggest that the interface layer between copper and aluminum primarily consisted of Al-Cu IMCs and Al-Cu eutectic alloy layers. As laser power increases, the thickness of the Al-Cu IMCs layer and the Al-Cu eutectic alloy layer gradually increased. Maximum tensile strength of 141.4 N/mm is achieved with IMCs layer thickness between 5.24 and 24.54 μm, the eutectic layer thickness between 8.81 and 22.41 μm, and weld interface thickness between 14.78 and 45.56 μm at a laser power of 2.6 kW.