Experimental study on magnetic field-assisted laser scanning welding of T2 copper

The study employed laser scanning welding technology for butt welding experiments on red copper, investigating the behavior of metal vapor plumes, plasma, and metal spatter during the welding process, as well as the quality and electrical conductivity of the resulting joints by varying the polarity and strength of the applied magnetic field. The results showed that the polarity of the magnetic field had a minor effect on welding performance, with the main influencing factor being the strength of the magnetic field. As the magnetic field strength increased, the formation volume and ejection intensity of metal vapor plumes and plasma exhibited an initial decrease followed by an increase, similarly affecting the weld seam morphology, mechanical properties, and electrical conductivity. At 120 mT magnetic strength, metal vapor and plasma formation are minimized, and metal spattering is eliminated, thereby enhancing welding stability; the weld seam was uniformly formed with no significant defects; the cross-sectional weld was even without obvious undulations; on one side of the weld zone, columnar crystals were extremely fine, and the center of the weld consisted of numerous equiaxed crystals with a few columnar crystals perpendicular to the horizontal direction, while the equiaxed crystals on the other side of the weld zone were denser; the sample joints achieved peak hardness and tensile strength at 70.9 HV and 202 MPa, showing increases of 17.2% and 14.8%, respectively, over nonmagnetic conditions; the weldment’s conductivity peaked at 79.58 mS/m, 36.5% higher than without a magnetic field, reaching 97.9% of the parent material’s.