What effect does excessive current have on the tungsten electrode?

Excessive current has a significant impact on the tungsten electrode, particularly leading to erosion. When the current exceeds the optimal level for the specific application, it heats the tungsten excessively, causing it to lose material. This erosion occurs as the high temperatures can vaporize parts of the electrode and contribute to contamination in the weld pool, which can adversely affect the quality of the weld. The contaminants can lead to poor fusion, increased porosity, and a compromised mechanical structure of the weld joint.

The other options do not accurately reflect the effects of excessive current on the tungsten electrode. For instance, while solidifying the electrode tip may seem beneficial, excessive heat typically results in the opposite effect. Increasing the lifespan of the tungsten is not feasible under high current conditions, as erosion leads to a shortened life span. Lastly, stating that excessive current has no effect is incorrect, as it clearly disrupts the balance needed for stable arc performance and weld integrity.