Which is a true characteristic of DCEN with GTAW?

Which is a true characteristic of DCEN with GTAW?

• A. Heat balance in arc is 70% at work end and 30% at electrode end
• B. Penetration is shallow and wide
• C. Oxide cleaning action occurs
• D. Electrode capacity is poor

Answer: (A)

In GTAW, using direct current with the electrode negative places electrons at the tungsten electrode and the workpiece becomes the positive electrode. This polarity concentrates most of the arc heat into the workpiece, with about 70% of the heat going to the work end and around 30% to the electrode. That heat balance explains why this option is true: it reflects how DCEN distributes heat, producing deeper, more focused penetration into the joint. The idea that penetration is shallow and wide isn’t consistent with DCEN, which tends to produce deeper, narrower penetration because the workpiece bears most of the heat. Oxide cleaning action is more associated with polarity changes or alternating current in GTAW, which helps remove oxide layers, rather than a hallmark of DCEN. And electrode capacity isn’t described as a defining characteristic of DCEN; the tungsten electrode remains non-consumable and its capacity isn’t characterized as poor in this context.

In GTAW, using direct current with the electrode negative places electrons at the tungsten electrode and the workpiece becomes the positive electrode. This polarity concentrates most of the arc heat into the workpiece, with about 70% of the heat going to the work end and around 30% to the electrode. That heat balance explains why this option is true: it reflects how DCEN distributes heat, producing deeper, more focused penetration into the joint.

The idea that penetration is shallow and wide isn’t consistent with DCEN, which tends to produce deeper, narrower penetration because the workpiece bears most of the heat. Oxide cleaning action is more associated with polarity changes or alternating current in GTAW, which helps remove oxide layers, rather than a hallmark of DCEN. And electrode capacity isn’t described as a defining characteristic of DCEN; the tungsten electrode remains non-consumable and its capacity isn’t characterized as poor in this context.