Abstract
Hybrid welding consisted of high power fiber laser and pulsed MAG arc was conducted on square-groove butt joint for SS400 of 12 mm thickness to investigate the optimum welding parameters for fully-penetrated weld bead formations by single pass. As a result, a sound fullypenetrated weld bead can not be obtained in laser leading-arc trailing process because irregular melt-through was observed in the bottom side weld beads under the all evaluated welding parameters. However, the formation of the irregular melt-through was suppressed effectively in arc leading-laser trailing process and sound fully-penetrated weld beads without any apparent defects was obtained successfully at the root gap up to 0.5 mm. Moreover, by using a high speed camera, it was revealed that the irregular melt-through was formed when amount of spatter was fluctuated on bottom side weld bead in laser leading-arc trailing process. However, in arc leading-laser trailing process, spattering constantly occurred and a stable molten metal pool was observed on bottom side weld bead. It was also found that the optimum laser and arc distance was below 4 mm, in which laser beam was irradiated onto the weld pool under the arc. From study results, the effect of hybrid welding parameters on the full penetration of 12 mm thick SS400 plate was systemically evaluated.
