How to Choose a Tungsten Electrode for AC and DC TIG Welding
Polarity decides everything about the electrode tip — how it heats, what shape it forms, and which oxide addition survives. Get the current right first, and choosing the electrode becomes easy.
What polarity does to the tip
On AC (used for aluminium and magnesium), the electrode alternately heats and cools each half-cycle. The tip melts into a rounded ball, which stabilizes the arc — that is why pure tungsten WP and zirconiated WZ8, both happy to hold a ball, are the classic AC choices.
On DCEN (electrode negative — the standard for steel, stainless, titanium and nickel), most heat goes into the workpiece, not the electrode. The tip stays sharp, so electrodes that keep a pointed or truncated-cone tip — lanthanated, ceriated and thoriated — give a focused, stable arc.
Choosing by material
- Aluminium / magnesium, AC: WP for general work; WZ8 for high current and cleaner beads.
- Steel, stainless, alloy — DCEN: WL15 / WL20 as the modern general-purpose pick; WT20 where thoriated stock is still required.
- Thin sheet / low amperage — DCEN: WC20 starts easiest at low current.
- Precision and critical DC work: WY20 for a concentrated, stable arc.
Three mistakes that shorten electrode life
- Too much amperage for the diameter. The tip overheats, oxides migrate and the arc wanders — step up one diameter or ask us for the current reference chart.
- Wrong tip shape for the current. Pointed tips on AC burn back; balled tips on DC wander. Match the grind to the polarity — see our grinding guide.
- Contamination. Touching the filler to the tip or dipping the electrode in the pool poisons it instantly — regrind before continuing.
Still unsure?
Tell us the material, thickness and your machine's amperage range — we will name the type, diameter and length, and quote it. Start the conversation.