Electrodes used in GMAW must be selected based on the ________ they are joining.

• A. Metals
• B. Alloys
• C. Thickness
• D. Welding position

Answer: (A)

In GMAW, you choose the electrode to match the metal you’re joining. The base metal’s composition and properties determine what filler wire is appropriate, so the weld has the right strength, ductility, and corrosion resistance. If you use a filler that isn’t compatible with the metal, you can get brittle joints, unwanted intermetallics, or severe corrosion.

For example, carbon steel commonly uses a low-alloy steel filler, aluminum uses aluminum alloy fillers such as 4043 or 5356, and stainless steel uses a stainless filler like 308L. These choices reflect the need to blend well metallurgically with the base metal. Thickness and welding position influence heat input and technique, but they don’t dictate which electrode to use—the base metal does. filler alloy choices also matter, but they’re guided by what metal is being welded, not the other way around.