The effect of shielding gas composition in CO2 laser—gas metal arc hybrid welding

• Published in: Proceedings of the Institution of Mechanical Engineers. Part B, Journal of engineering manufacture Vol. 222; no. 11; pp. 1315 - 1324
• Main Authors: Chae, H-B, Kim, C-H, Kim, J-H, Rhee, S
• Format: Journal Article
• Language: English
• Published: London, England SAGE Publications 01.11.2008; Sage Publications; SAGE PUBLICATIONS, INC
• Subjects: Applied sciences; Argon; Carbon dioxide; Composition effects; Dioxides; Exact sciences and technology; Gas composition; Gas metal arc welding; Helium; High speed; Joining, thermal cutting: metallurgical aspects; Laser beam welding; Lasers; Mechanical engineering. Machine design; Metallurgy; Metals. Metallurgy; Plasma; Plasma arc welding; Plasmas (physics); Retarding; Shielding; Shipbuilding; Stability; Studies; Welding; Wetting; laser-induced plasma; hybrid welding; CO2 laser welding; shielding gas; gas metal arc welding (GMAW); Weld metal; Molten state; Wetting; Carbon dioxide; Power laser; Laser assisted processing; Composition effect; Droplet; Helium; CO; Laser welding; Gas laser; Gas shielded arc welding; laser; Metal transfer; Shielding effect; High speed cinematography; GMA welding
• ISSN: 0954-4054; 2041-2975
• DOI: 10.1243/09544054JEM944

In carbon dioxide (CO2) laser—gas metal arc hybrid welding, a shielding gas is supplied to isolate the molten metal from the ambient air, suppress the laser-induced plasma, remove the plume out of the keyhole, and stabilize the metal transfer. In this study, a shielding gas consisting of helium, argon, and CO2 was used, and its effects on the composition of the welding phenomena, such as behaviours of laser-induced plasma generation, molten pool flow, and droplet transfer in gas metal arc welding, were investigated. High-speed video observation was used to investigate the welding phenomena inside the arc regime. Consequently, helium was found to have a dominant role in suppressing laser-induced plasma; minimum helium content at a laser power of 8 kW was suggested for laser autogenous and hybrid welding. Argon and CO2 govern the droplet transfer and arc stability. A 12 per cent addition of CO2 stabilizes the metal transfer and eliminates undercut caused by insufficient wetting of molten metal.