The aluminum (Al) alloy double-wire pulsed gas metal arc welding (GMAW) has severe double arc interference issues. To reduce double arc interference, the advantages of double-wire pulsed GMAW and variable-polarity (VP) welding are combined to form Al alloy double-wire VP double base pulsed GMAW. The profile and behavioral characteristics of double arcs are analyzed using high-speed images to assess their physical properties. The arc load characteristics are explored through U-I curves, and the polarity switching process is analyzed from the perspective of double arc coupling. The experimental results showed that arcs with identical polarity are attracted to each other, while arcs with the opposite polarity repel each other. The coupling areas of two arcs with different polarities are therefore different; the electrode positive (EP) arc has a broader profile, while the electrode negative (EN) arc has an elongated profile. The stability of the leading arc is also affected by the polarity switching of the trailing arc. During the EN phase, the trailing arc can climb up to 2–3 times the wire diameter along the wire to search for metal oxide. The EN arc is more stable than the EP arc, and the EN peak arc has a load impedance that is 0.4–0.6 times lower than that of the EP peak arc. The polarity switching from EP to EN is easier due to the larger arc coupling area while switching from EN to EP is more difficult because of the thin arc coupling area. Regardless of polarity, the arc coupling area can provide charged particles for the arc to a certain extent and reduce the probability of arc extinguishing due to polarity switching.
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