When using pure tungsten or zirconiated electrodes on AC, what forms at the tip of the electrode?

When using pure tungsten or zirconiated electrodes on AC, what forms at the tip of the electrode?

• A. A hemispherical ball
• B. A sharp chisel point
• C. A flat tip
• D. A spiral tip

Answer: (A)

A hemispherical ball forms at the tip. When using pure tungsten or zirconiated electrodes on alternating current, the electrode tip is repeatedly heated in both half-cycles. Molten tungsten has strong surface tension, so the tip tends to round off into a ball rather than stay sharp. This ball shape helps keep the arc stable on AC and avoids the tip wear that would come from trying to maintain a sharp point. Sharp chisel points are more typical for DC welding, while flat or spiral tips aren’t standard outcomes for AC with these electrodes.

A hemispherical ball forms at the tip. When using pure tungsten or zirconiated electrodes on alternating current, the electrode tip is repeatedly heated in both half-cycles. Molten tungsten has strong surface tension, so the tip tends to round off into a ball rather than stay sharp. This ball shape helps keep the arc stable on AC and avoids the tip wear that would come from trying to maintain a sharp point. Sharp chisel points are more typical for DC welding, while flat or spiral tips aren’t standard outcomes for AC with these electrodes.