1. The brighter and more uniform the surface, the less grinding marks and black spots, and the better the tungsten electrode.

2. The less internal bruises and the smaller the bruises, the better the tungsten electrode.

3. The less the diameter negative difference, the more durable the tungsten electrode.

4. The internal molecular structure of annealed tungsten electrode is more stable, but because of the higher requirements of sharpening and easy fracture, it is not recommended in China and is mainly used for export requirements, so it is a technical difficulty to achieve molecular stability without annealing.

Principle: tungsten electrode welding is current through the entire length of tungsten electrode to the end, and therefore the greater the stability of the molecular structure of tungsten, the less the current value, the lower the power, thus the more durable, more surface and internal defects, in use, the greater the output current, the more the heat generated, the faster the loss, if internal flaws, cracks, welding current is big and instability, it's easy to have a partial arc, bifurcate, so after the inspection standard as one of the most important indicator of quality.