Single pass hybrid laser-arc welding of 25 mm thick square groove butt joints

An innovative hybrid laser-arc welding technique has been developed for one-pass welding of 25 mm thick steel plates. The parts to be welded were assembled into a butt joint configuration with a square groove and 2.5 mm air gap. A backing method was applied using ceramic strip or submerged arc welding flux. Cut-wire particles were inserted into the joint gap to protect the backing material from laser radiation and in the same time help to fill the gap. Laser power density was optimized to obtain full penetration joints without damaging the backing material. Defect-free joints with adequate fusion zone profiles and good mechanical properties were successfully produced. The technique was then applied to weld 50 mm thick plates in two welding passes. Using the same joint design, one welding pass was overlaid from one side of the joint and a second pass was deposited from the other side. In this case, a backing plate of any material could be used since the laser radiation does not reach the bottom side of the joint. (C) 2016 Elsevier Ltd. All rights reserved.