In GTAW, which gas has been combined with which to gain the benefits of cathode cleaning and deeper penetration?

• A. Helium with Argon
• B. Argon with Helium
• C. Hydrogen with Argon
• D. Nitrogen with Helium

Answer: (B)

In GTAW, the shielding gas shapes the arc and how heat is delivered to the metal. Helium makes the arc hotter, increasing heat input and giving deeper penetration, but it can make the arc harder to stabilize. Argon, on the other hand, provides a stable arc and good shielding, helping keep the weld surface clean. Mixing argon with helium combines these benefits: helium drives deeper penetration while argon keeps the arc stable and supports effective shielding and cleaning at the cathode and weld pool. So using an argon–helium mixture gives both cathode cleaning benefits and deeper penetration.