LASER-MIG Hybrid Welding of Thick Plates of Mild Steel in Single Pass

Laser hybrid welding combines the deep penetration capability of laser beam and edge gap bridging capability of an arc welding process such as MIG/MAG. In the present work, a 3.5 kW slab CO₂ LASER -MIG hybrid welding system was used to carry our laser hybrid welding studies with an aim to achieve butt welds of 12mm thick mild steel plates in single pass. Bead-on-plate studies were carried out to first understand the effect of parameters such as laser power, focal plane position of the laser, MIG wire feed rate, composition of shielding gas, distance between laser and MIG arc on the weld penetration. The optimized parameters were then applied on butt welds with Y-groove edge preparation with varying ischolar_main face height and groove angle to identify suitable joint design. Combining the results of bead-on-plate experiments and butt welding experiments, welding of 12 mm thick mild steel plates in single pass could be achieved. The LASER-MIG hybrid butt welds so fabricated showed 100% joint efficiency and high bend ductility.