For TIG welding aluminum, which shielding gas is typically used?

• A. 100% Nitrogen
• B. 100% Argon
• C. 50% Helium
• D. Air

Answer: (B)

Shielding gas for TIG welding aluminum is chosen to protect the molten pool from oxidation and contamination while providing a stable arc. Pure argon is the standard choice because it’s inert, affordable, and gives excellent arc stability and weld cleanliness for aluminum, whether you’re welding with DC or AC.

Using nitrogen isn’t appropriate because it’s not inert for welding and can interact with aluminum to form undesirable compounds, leading to weaker or defective welds. Air isn’t used because its oxygen and moisture would oxidize the molten metal and introduce porosity and surface contamination. A helium-containing mix can alter heat input and arc characteristics, but it’s not the typical, go-to shielding gas for aluminum TIG welds.