For welding mild steel in GTAW, which polarity is recommended?

In Gas Tungsten Arc Welding (GTAW) for mild steel, the recommended polarity is Direct Current Electrode Negative (DCEN). This polarity configuration provides several benefits that are crucial for achieving a high-quality weld.

When using DCEN, the majority of the heat is concentrated at the workpiece (the base metal), which allows for deeper penetration and a more effective weld. This is especially important for mild steel, as it can help ensure that the weld fuses properly with the base metal, creating a strong bond. The lower heat at the electrode also helps to prolong its life, as less wear occurs due to decreased heat concentration on the tungsten electrode.

In comparison, Alternating Current (AC) and Direct Current Electrode Positive (DCEP) do not provide the same level of efficiency for mild steel welding. AC is generally used for aluminum and magnesium because it can better accommodate the cleaning action required for these materials. DCEP can produce a hotter arc but tends to drive more heat into the electrode than the workpiece, which is not desirable when welding mild steel, as it can lead to a lack of penetration and greater electrodic wear.

Overall, DCEN is the optimal polarity for GTAW on mild steel, enabling effective heat application