Parametric Study on One Pass Fully-Penetrated Weld Bead Formation in Horizontal Fillet Weld T-Joint by Fiber Laser-MAG Arc Hybrid Welding for Thick Steel Plate

This paper deals with the characteristics of bead formation in horizontal fillet T-joint of 12 mm thick SS400 plate using high power fiber laser and pulsed MAG arc hybrid welding. One pass fully-penetrated sound weld bead without void or pit was successfully obtained in laser leading condition at the optimized welding conditions including laser aiming offset on the vertical plate from joint line and laser irradiation angle. In the case of arc leading void or pit was likely to form in the weld bead, and sound weld bead was difficult to obtain. It was also revealed that metal supplied by welding wire was concentrated on the upper side of weld bead, which was made mainly by arc welding, and difficult to mix into the bottom part of weld bead, which was made mainly by laser welding, in both arc and laser leading conditions. Lack of fusion and hot cracking occurred, but can be suppressed by setting the optimum welding speed and arc current to modify the shape of weld penetration.