MCAWGalvanized and coated steels are frequently welded and metal cored wires are often used for this purpose. Standard MIG equipment is suitable, and the wire composition is chosen to closely match the parent steel, which is usually a mild steel type. Metal cored wires do not contain fluxing agents, but manufacturers have developed some metal cored wires to make them more suitable for welding galvanized and painted steels. Argon-20%CO2 is the more common shielding gas but some wires will operate under pure CO2. The main problems with welding galvanized plate are porosity, particularly in the roots of fillet welds, possible cracking, spatter, and zinc oxide fume. With other coatings porosity and spatter can be serious problems and fume from some coatings may be toxic. The main safety issues are potentially toxic fume, electrical, radiation, spatter, and compressed inert gases.
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