A welding supervisor observes a welder struggling with poor arc stability and excessive spatter during GTAW on 8 mm thick aluminum using AC. The welder is using a 3.2 mm diameter 2% lanthanated tungsten electrode with a sharply ground point. What primary adjustment should the supervisor recommend concerning the electrode?

Question: A welding supervisor observes a welder struggling with poor arc stability and excessive spatter during GTAW on 8 mm thick aluminum using AC. The welder is using a 3.2 mm diameter 2% lanthanated tungsten electrode with a sharply ground point. What primary adjustment should the supervisor recommend concerning the electrode?

Answer options:

• Increase the shielding gas flow rate. ✅ Switch to a pure tungsten electrode and form a small spherical ball on the tip.
• Decrease the welding current by 20 amps.
• Increase the electrode stick-out from the torch nozzle.

Correct answer: Switch to a pure tungsten electrode and form a small spherical ball on the tip.

Explanation: 2% lanthanated tungsten is generally more suited for DC welding due to its higher melting point and tendency to not form a stable ball with AC current. For AC welding on aluminum, a pure tungsten electrode, which naturally forms a stable spherical ball, is preferred as it considerably improves arc stability and reduces spatter. Grinding a point on any electrode type for AC welding aluminum will lead to overheating and instability.