Which inert gas is most commonly used as shielding gas in GTAW today?

• A. Argon
• B. Helium
• C. Neon
• D. Krypton

Answer: (A)

In GTAW, shielding gas serves to protect the molten weld from the atmosphere and to influence arc stability and heat input. Argon is the most commonly used shielding gas because it is inert, provides a stable arc across a wide range of currents, and works well with both AC and DC welding. This combination makes it versatile for many metals, producing clean beads and good control without adding reactive species to the weld. It’s also cost-effective and readily available, making it the default choice for most GTAW applications. Helium is used only when extra heat input is needed (thicker sections or a need for deeper penetration), but it is more expensive and can widen the bead. Neon and krypton are rarely used in practice due to cost and less reliable arc performance for typical GTAW tasks.