Consumables – Shielding Gas

Shielding gases for GTAW, GMAW and FCAW-G processes are used to shield the welding arc and molten weld metal from nitrogen and oxygen in the atmosphere. Inert shielding gases (argon and helium) are required for the GTAW process to avoid contamination of the tungsten electrode. The most common shielding gases for the GMAW and FCAW-G processes are Ar, CO2, and combinations of the two. The exact shielding gas composition is selected to provide the desired bead shape and to minimize spatter. (100% CO2 shielding is cheaper but produces greater amounts of spatter.) Other less common shielding gases are also acceptable. Ar-O2 mixtures are sometimes used for low alloy steels (e.g., 2¼ CR-1Mo) and He-Ar-CO2 mixtures are sometimes used for austenitic stainless steels (i.e., Type 304L). Refer to Appendix A of the Welding Manual for various alloys and welding processes.

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