Influence of the CO2 content in the shielding gas on metal transfer of the double wire MIG/MAG process

Double Wire MIG/MAG welding process appeared in manufacturing market as an alternative for increasing producitivity. As an unusual technology, a better knowledge of it is fundamental for enlarging its industrial application. Therefore, the objective of this work was to evaluate the influence of using shielding gas with different CO2 contents, at the same current level, on metal transfer modes and bead geometry profiles. Using a torch with a single electrical potential, a series of weldments was carried out at 3 different arc length conditions. The visualization of the metal transfer was possible by using the technique of shadowgraphy, while geometry was evaluated from macrographies of weld bead transverse sections. Longer arcs lead to large beads and higher deposition rates. A trend towards more stable transfer, higher deposition rates and deeper penetration was observed for the shielding gas with the lower CO2 content. In contrast, the higher level of CO2 produced high thermal efficiency and larger beads.