Which process is most likely to be performed without any shielding gas?

Which process is most likely to be performed without any shielding gas?

• A. SMAW
• B. FCAW (self-shielded)
• C. GMAW
• D. GTAW

Answer: (B)

Shielding of the weld pool is what keeps it from reacting with the surrounding air. Some welding methods rely on shielding gas, while others generate shielding from fluxes built into the electrode or wire. The self-shielded flux-core option provides its own shielding through the flux inside the wire; as you weld, the flux decomposes and releases gases and slag that protect the molten weld without needing any external shielding gas supply. That’s why this method is described as not requiring shielding gas from an outside source. The other options typically depend on an external shielding gas (or are not inherently self-shielding in common practice), so they aren’t without shielding gas.

Shielding of the weld pool is what keeps it from reacting with the surrounding air. Some welding methods rely on shielding gas, while others generate shielding from fluxes built into the electrode or wire. The self-shielded flux-core option provides its own shielding through the flux inside the wire; as you weld, the flux decomposes and releases gases and slag that protect the molten weld without needing any external shielding gas supply. That’s why this method is described as not requiring shielding gas from an outside source. The other options typically depend on an external shielding gas (or are not inherently self-shielding in common practice), so they aren’t without shielding gas.