What are welding gases? Welding fumes are a complex mixture of metallic oxides, silicates and fluorides. Fumes are formed when a metal is heated above its boiling point and its vapours condense into very fine, particles (solid particulates).
How do welding gases vary in what they contain?Welding fumes contain oxides of the metals in the materaal being welded. Fluxes containing silica or fluoride produce amorphous silica, metallic silicates and fluoride fumes. Fumes from mild steel welding contain mostly iron with small amounts of additive metals (chromium, nickel, manganese, molybdenum, vanadium, titanium, cobalt, copper etc.). Stainless steels have larger amounts of chromium or nickel in the fume and lesser amounts of iron. Nickel alloys have much more nickel in the fume and very little iron.