Pure tungsten electrode is the earliest electrode that applied for argon arc welding, and it is only used as a welding electrode or a resistance welding electrode under AC conditions as this type of electrode is prone to appear the phenomenon of no arc or pilot arc instability under DC welding conditions. This problem can be greatly approved by adding rare earth oxides.
Generally, the tip of pure tungsten electrode is spherical, and is used in the process of sine wave and traditional square wave argon arc welding. After the sphere is formed, it is usually applied for alternating current to know the diameter of the electrode, and eventually it will have its own form. The diameter of the sphere should not exceed 1.5 times the diameter of the electrode (For example, the diameter of the sphere is 1/8, then the diameter of the electrode is 3/16), as the electrode with a larger spheroid at the tip can reduce the arc stability and even drop off. Also, it will make the welding line be contaminated.
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