The Effect of Different Laser Processing Parameters on the Microstructure and Properties of Copper Conductor Joints

To mitigate welding defects in copper wire conductors induced by their high laser reflectivity and thermal conductivity during laser welding, this study combines numerical simulation and experimental testing to investigate the influences of laser processing parameters on the mechanical properties, molten pool dynamic evolution, and microstructural characteristics of copper self-fusion welds and pure Ni powder-filled welds. The results demonstrate that, for self-fusion welding, a moderate increase in laser power and welding time elevates the heat input, which promotes weld penetration and forming quality. The optimal parameter combination (3900 W, 1.0 s) yields a balanced internal densification and grain refinement, with the joint tensile strength reaching a peak of 245 MPa. For Ni powder-filled welding, the infinite solid solubility between Cu and Ni improves interfacial metallurgical bonding. Under the optimal parameters (3500 W, 1.2 s), the joint tensile strength increases to 282 MPa. Heat input exerts a significant effect on the temperature field evolution in both welding processes, yet the molten pool expansion behaviors differ: self-fusion welding exhibits continuous expansion with rising heat input, whereas Ni powder-filled welding displays complex nonlinear variations.