DEVELOPMENT OF ADVANCED 3-ELECTRODE MAG HIGH-SPEED HORIZONTAL FILLET WELDING PROCESS

摘要

In the shipbuilding industry, the improvement of welding efficiency and weld quality are desirable in order to cope with the recent growth in shipbuilding orders and the size of ship hulls. Innovation in welding efficiency and weld quality in horizontal fillet welding is an important issue since the amount of horizontal fillet welding work generally accounts for 70 percent or higher of the total welding work for ship hulls. As one of the available high-speed horizontal fillet welding processes, the Twin Tandem One Pool process (hereinafter referred to as the TOP process) has been used in actual fabrication. In the TOP process, a set of two wire electrodes is positioned in tandem on both sides of the web plate of a fillet joint and the wire-to-wire distance is kept short, so as to create one weld pool. However, the maximum welding speed of the TOP process is approximately 1.5 m/min. In order to improve the welding speed of the TOP process, the authors have employed an additional filler wire positioned between the two wires of the TOP process. The additional filler wire carries DC-EN currents, as opposed to DC-EP currents for the main welding wires, thereby reducing the arc interference and arc blow at high currents. With this new technique, the authors have improved the stability of the weld pool formation at high currents. Consequently, horizontal fillet welding at a speed of 2.0 m/min on primer-coated steel plates has been achieved with excellent bead appearance, shape and porosity resistance.