For DC welding, which tungsten option pairs a 1% thorium electrode with an additional thorium-bearing electrode?

• A. Zirconium bearing electrode
• B. 1% thorium electrode with 2% thorium bearing electrodes
• C. Green tungsten
• D. Brown tungsten

Answer: (B)

In DC TIG welding, tungsten electrodes that contain thorium oxide emit electrons more readily, which helps start and stabilize the arc, especially at higher currents. A 1% thorium electrode is a common choice for general DC welding because it provides good arc initiation and stable performance. When you pair that with an electrode containing 2% thorium oxide, you’re bringing in even higher emission capability, which can improve arc stability and current handling in more demanding DC welds.

The other options describe tungsten types that do not include thorium, so they don’t represent a thorium-containing pairing. Pure tungsten (no thorium) and zirconiated tungsten (without thorium) lack the enhanced electron emission that thorium-bearing electrodes provide, which is why they aren’t the correct pairing for this question. Keep in mind that thorium-bearing electrodes require careful handling due to radioactivity.