Arc characteristics and metal transfer behavior in narrow gap gas metal arc welding process

Abstract

During the constant-voltage welding machine employed welding process, a common phenomenon of arc attachment point moving from the bottom of the narrow gap to the sidewalls occurs, and metal transfer behavior appears greatly different. A mechanism that the arc inherent-self regulation combines the minimum arc voltage principle was proposed to elaborate the arc climbing up process along the sidewalls. The arc shape was approximately classified into three patterns by the change of arc conductive path, and the amount of the arc conductive path and its distributive symmetry determine the action of the electromagnetic force on the droplet as well as the metal transfer mode. As the number of the arc conductive paths increases, and the conductive paths distribute symmetrically, the necking process of the droplet detachment occurs more easily, and the metal transfer from globular mode to spray mode becomes more smoothly. Simulation results match the experiments and verify the mechanism proposed. In a constant-current welding power source adopted condition, the arc climbing up phenomenon cannot be observed, and a stable welding process is obtained.