Expansion of laser–arc hybrid welding to horizontal and vertical-up welding

Abstract

Laser–arc hybrid welding (LAHW) is an advanced welding method that combines arc welding and laser welding and can achieve deep penetration and the reduction of welding deformation compared with conventional arc welding. As with other welding techniques, it is common to target the flat position (PA) as the welding position. However, the expansion of the applicable positions enables the application of high-quality welded joints fabricated by LAHW to many welded joints in large steel structures. This study used the LAHW system with a robot manipulator to establish weldability in the horizontal position (PC) and the vertical-up position (PF) to expand the applicable range of LAHW in large steel structures. Suitable LAHW conditions for fabricating the butt-welded joint with a welding length of 1,000 mm for these positions were established through various investigations, including molten pool observation. Finally, the quality of these joints was evaluated in accordance with the laser–arc hybrid welding guidelines (ClassNK) of Nippon Kaiji Kyokai, and it was confirmed that the joints satisfy the required standards.