Abstract
High-power lasers are very effective in welding of plates thicker than 10 mm due to the keyhole mode. High-power intensity
generates a vapor-filled cavity which provides substantial penetration depth. Due to the narrow and deep weld geometry, there is
susceptibility to high hardness and weld defects. Imperfections occur due to keyhole instability. A 16-kW disk laser was used for
single-pass welding of 12- to 15-mm thick plates in a butt joint configuration. Root humping was the main imperfection and
persisted within a wide range of process parameters. Added arc source to the laser beam process may cause increased root
humping and sagging due to accelerated melt flow. Humping was mitigated by balancing certain arc and other process parameters. It was also found that lower welding speeds (< 1.2 m/min) combined with lower laser beam power (< 13 kW) can be more
positive for suppression of humping. Machined edges provided more consistent root quality and integrity compared with plasma
cut welded specimens. Higher heat input (> 0.80 kJ/mm) welds provided hardness level below 325 HV. The welded joints had
good Charpy toughness at − 50 °C (> 50 J) and high tensile strength
generates a vapor-filled cavity which provides substantial penetration depth. Due to the narrow and deep weld geometry, there is
susceptibility to high hardness and weld defects. Imperfections occur due to keyhole instability. A 16-kW disk laser was used for
single-pass welding of 12- to 15-mm thick plates in a butt joint configuration. Root humping was the main imperfection and
persisted within a wide range of process parameters. Added arc source to the laser beam process may cause increased root
humping and sagging due to accelerated melt flow. Humping was mitigated by balancing certain arc and other process parameters. It was also found that lower welding speeds (< 1.2 m/min) combined with lower laser beam power (< 13 kW) can be more
positive for suppression of humping. Machined edges provided more consistent root quality and integrity compared with plasma
cut welded specimens. Higher heat input (> 0.80 kJ/mm) welds provided hardness level below 325 HV. The welded joints had
good Charpy toughness at − 50 °C (> 50 J) and high tensile strength