What is a key difference between FCAW and GMAW?

• A. FCAW uses a solid wire
• B. FCAW uses a tubular wire electrode
• C. GMAW uses flux-core wire
• D. GMAW requires no shielding gas

Answer: (B)

The main idea here is how the electrode is constructed. FCAW uses a tubular wire electrode that is filled with flux. This flux inside the tube provides shielding and often adds alloying elements or produces slag, depending on the type. GMAW, on the other hand, uses a solid wire electrode and relies on an external shielding gas to protect the weld pool. Because the defining difference between FCAW and GMAW is that FCAW uses a tubular flux-filled electrode, the statement about a tubular wire electrode best captures what sets the two processes apart. The other options mix up the electrode type or the shielding method, which are not the distinctive feature being tested.