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

Abstract

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.

A computational fluid dynamic analysis of the effect of side draughts and nozzle diameter on shielding gas coverage during gas metal arc welding

“…The arc temperature was then systematically increased in Fluent until the correct heat transfer from arc to plate was achieved in the model. This occurred at a value of 32,000 K, higher than that determined by Jönsson et al However this was expected given a shielding gas mixture of 80%Ar/20%CO 2 was used and CO 2 is known to Chae et al (2008). It was therefore anticipated that greater penetration would be the result of an increased arc temperature when compared to that of pure argon.…”

“…An argon/carbon dioxide (80/20) mixture is a commonly used GMAW shielding gas in Western Europe, particularly in carbon steel fabrication industries. In such cases, carbon dioxide is routinely added to an argon-based mixture as it has the ability to stabilize the arc and produce a more consistent weld than argon on its own as demonstrated by Chae et al (2008).…”

Simulation and Modeling of Shielding Gas on the Welding Defects in the Fiber Laser Keyhole Welding

“…The highest tensile strength in their experiments was acquired from the sample which was produced under shielding gas of 1.5% H 2 -Ar. Chae et al [11] confirmed that laser-induced plasma generation was in inverse proportion to penetration depth. Their experiments revealed that helium content in shielding gas affected the laser-induced plasma generation and further played an important role in welding quality.…”

Evaluation of the Shielding Gas Influence on the Weldability of Ferritic Stainless Steel

“…The same authors believe that a small amount of CO 2 added to argon should be used for short-circuiting transfer. According to Chae et al (2008), the addition of CO 2 to argon improves the wettability of the weld bead, improving the weld quality. However, Strassburg (1976) claims that an increase in the proportion of oxidizing elements in the shielding gas increases the loss of molybdenum, chromium and niobium.…”