Which polarity results in welds with deep penetration and allows use of a smaller tungsten electrode?

• A. Direct Current Reverse Polarity
• B. Direct Current Electrode Negative
• C. Alternating Current High Frequency
• D. Direct Current Electrode Positive

Answer: (B)

In GTAW, where the heat goes is controlled by polarity, and that directly affects how deep the weld penetrates. Negative polarity (Direct Current Electrode Negative) concentrates most of the heat into the workpiece, which creates deeper penetration. It also allows using a smaller tungsten electrode because the arc energy is focused at the base material rather than eroding the electrode. In contrast, positive polarity (Direct Current Electrode Positive) puts more heat into the electrode, leading to faster electrode wear and shallower penetration. Alternating current with high frequency isn’t aimed at maximizing penetration with a small electrode, as it cycles polarity and is used more for cleaning action and stability, especially on aluminum.