What does a blue-to-purple or blackened end of a tungsten electrode indicate?

A blue-to-purple or blackened end of a tungsten electrode indicates insufficient flow of shielding gas. In the Gas Tungsten Arc Welding (GTAW) process, the shielding gas, typically argon, protects the weld area and the tungsten electrode from atmospheric contamination. If the flow of shielding gas is inadequate, it can lead to oxidation of the tungsten. The color change to blue, purple, or black is a visual indicator that this protective atmosphere has been compromised. Proper shielding gas flow is essential for maintaining the integrity of the tungsten electrode and ensuring high-quality welds.

This scenario often occurs in practice when the settings on the gas regulator may be incorrect or the gas source might have been obstructed, leading to insufficient coverage of the weld area. Hence, recognizing and addressing inadequate shielding gas flow is crucial to prevent detrimental effects on the welding process.