Steel Welding Fume
Welding fume will be produced during arc welding of carbon and alloy steel. Fume comprises particulate fume, which you can see, and gaseous fume, which is not visible. Most of the particulate fume comes from the consumable. Particulate fume from mild steel and carbon steels tends to be comprised of iron oxide plus some manganese oxide. Alloy steel fume will also contain oxides of whichever alloying elements are present. If gaseous fume is produced the most important component is ozone, a reactive, toxic, gas. MIG welding produces particulate fume and may give some ozone. The particulate fume will additionally contain copper, if a copper coated filler wire is used. Ozone may be formed with argon-rich shielding gases but not with pure CO2. MMA welding gives only particulate fume. As well as iron and manganese, it may also contain fluorides if basic coated electrodes have been used. Welding with cored wires will give particulate fume and may give ozone at high current in argon mixtures. Generally the fume will contain iron and manganese, plus fluorides from basic wires. Some self-shielded wires may also give barium in the fume. In general terms, as process current increases, so does fume production. Under normal circumstances, TIG and submerged arc welding produce very little fume at all. Iron oxide fume is not thought to present a serious hazard to health and other alloying constituents, manganese, nickel, and chromium only tend to be produced in low concentrations. Appropriate fume extraction equipment should be used to keep fume levels to an acceptable level. If ozone is generated then precautions must be taken to keep exposure to a minimum.
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