What is the common shielding gas for TIG welding?

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

Answer: (C)

In TIG welding, shielding gas protects the molten pool from the air and helps stabilize the arc, which directly affects weld cleanliness and bead shape. Argon, used as 100% shielding gas, is the most common because it’s inert and provides excellent arc stability, good penetration, and clean welds across many metals, while also being affordable and widely available. Other options exist in specific cases: helium can be used when extra heat input is desired (or for certain aluminum welding scenarios), and blends of argon with helium are chosen for particular thicknesses or materials. Nitrogen isn’t used as a shielding gas in TIG because it can react with the molten metal, causing defects like nitrides.