Which practice minimizes erosion of the tungsten electrode in GTAW?

• A. Using AC
• B. Using DCEN
• C. Using DCEP
• D. Using an air-cooled torch

Answer: (B)

The main idea is how polarity affects where most of the arc heat goes, which in turn drives tungsten erosion. Tungsten erosion happens when the electrode overheats and its tip deforms or dissolves. Using direct current with the electrode negative concentrates more heat in the workpiece and leaves the tungsten cooler, so the tip erodes much less and lasts longer. When the electrode is positive (electrode positive, workpiece negative), more heat is dumped into the tungsten tip, accelerating erosion. Alternating current reverses polarity, causing heating of both sides over time and can wear the tungsten more quickly. An air-cooled torch helps manage temperature, but the best way to minimize erosion is to run with the electrode negative (DCEN), which keeps the tungsten cooler while still achieving good weld penetration.