1：Experimental Design and Method Selection:

The study involved bead-on-plate experiments of oscillating laser-MIG hybrid welding on pure Al plate using ER4047 Al filler wire. The setup included an IPG YLR-6000 fiber laser, a laser welding head with a galvanometer scanner, a FRO-NIUS TPS4000 MIG arc welder, and a FUNAC M-710ic/50 robot. The beam oscillation pattern was circular oscillation.

2：Sample Selection and Data Sources:

Pure Al plate (1A99) with 12 mm thickness and ER4047 Al filler wire (Al-12Si) with 1.2 mm diameter were used.

3：2 mm diameter were used. List of Experimental Equipment and Materials:

3. List of Experimental Equipment and Materials: IPG YLR-6000 fiber laser, FRO-NIUS TPS4000 MIG arc welder, FUNAC M-710ic/50 robot, Phantom V710 high-speed camera with Cavitar Cavilux HF illumination.

4：Experimental Procedures and Operational Workflow:

The welding parameters included laser power 5000 W, arc current 200 A, wire feeding rate 9 m/min, welding speed 2 m/min, and laser defocused distance 0 mm. The varied parameters were beam oscillating amplitude A (0.2–1.0 mm) and frequency f (0–500 Hz).

5：2–0 mm) and frequency f (0–500 Hz). Data Analysis Methods:

5. Data Analysis Methods: The Si concentration in the welds was detected using laser-induced breakdown spectroscopy (LIBS), and the macrosegregation was quantitatively analyzed based on the Si distribution variation.