The gray tungsten electrode represents the cerium tungsten electrode, and the chemical symbol indicates: WC20.
Blue tungsten represents pure tungsten electrodes, chemical symbol: WP.
Specifications and shapes of common tungsten electrodes used in argon arc welding:
1. Taper: suitable for small current welding and butt weld plate bending.
2. Arc shape: it is suitable for welding AC power supply, but the arc is unstable when the direct current is connected.
3. Cylindrical: suitable for welding aluminum and magnesium alloys. But direct current connection method is not available.
4. Flat bottom form: suitable for direct current connection, arc concentration, stable combustion, good weld formation.
Proper use of tungsten electrode can achieve arc stability and prolong the service life of tungsten electrode. When the tungsten pole type is selected, its shape and size become critical when used. The shape of the tungsten tip has an influence on the arc stability. If the end surface is uneven, the arc is not concentrated and unstable. It must be sharpened before use, and the degree of sharpening is related to the diameter of the wire and the magnitude of the current used. When welding thin plate and small welding current, small diameter tungsten electrode can be used to grind the end of the electrode so that the arc is easy to ignite and be stable, therefore, the cone angle should be appropriately enlarged or conical with flat top. When AC TIG welding is used, tungsten ends are usually semi spherical, and with the increase of current, the diameter of the tungsten electrode increases, and the maximum is equal to the tungsten electrode radius (without taper angle). With the increase of the terminal cone angle of tungsten electrode, the diffusion tendency of arc column decreases, while the penetration depth increases, the weld width decreases, and the cross-sectional area of welding seam is almost unchanged. The more the current is, the more obvious the phenomenon is.
