for Flux Core Arc Welding (FCAW)
majority of flat-position large-diameter (> 1/16")
flux-cored wires that use a secondary shielding gas use carbon
dioxide. The arcs are generally quiet with high deposition rates
and are good for welding over rust and mill scale on heavy plate.
Dioxide Mixtures. Most
of the small-diameter (< 1/16") and all position cored
wires use an argon-based shielding gas. These gas blends provide
greater weld puddle control lower welding fume and are preferred
by welders because of ease of use.
amounts of oxygen may be added to argon for welding carbon steels;
however, shielding gas blends, such as argon-2% oxygen, are used
primarily for Gas Metal Arc Welding (GMAW) of stainless steels.