Tungsten electrode

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Tungsten electrodes are required for tungsten inert gas welding (TIG). Depending on the type of current, pure tungsten electrodes or those with oxidic additives are used; they are color-coded according to the type and quantity of the additive. The electrodes are classified according to ISO 6848, last status 2015. Not all electrodes listed here can be found in the standard, such as the WS, WT40 or WT4.

designation composition Identification color
WP pure tungsten green
WZr 3 0.15-0.50% zirconium (IV) oxide brown
WZr 8 0.70 to 0.90% zirconium (IV) oxide White
WT 4 0.35 to 0.55% thorium dioxide - radioactive ! Light Blue
WTh 10 0.80 to 1.20% thorium dioxide - radioactive! yellow
WTh 20 1.70 to 2.20% thorium dioxide - radioactive! red
WTh 30 2.80 to 3.20% thorium dioxide - radioactive! violet
WT 40 3.80 to 4.20% thorium dioxide - radioactive! orange
WLa 10 0.80 to 1.20% lanthanum oxide black
WLa 15 1.30 to 1.70% lanthanum oxide gold
WLa 20 1.80 to 2.20% lanthanum oxide dark blue
WCe 20 1.80 to 2.20% cerium (IV) oxide Gray
WS 2 ® Rare earths (mixed oxides) turquoise

The WP electrodes are pure tungsten electrodes and are mainly used for AC welding. The WZ electrodes have slightly better properties for AC welding.

The WTh electrodes are slightly radioactive due to the addition of thorium . With direct current welding, they have better ignition properties and a higher current carrying capacity than pure tungsten electrodes. The use of these electrodes should be avoided; The grinding of these electrodes in particular requires special care and special extraction systems.

The WCe , WL and WS electrodes are used for direct and alternating current welding , they are a full replacement for the WT electrodes. Compared to WC, WLa is somewhat better suited for small currents. The WS electrodes are usually a bit more expensive and have different, non-standardized compositions. Service life and resilience should be even higher.

Grinding: Tungsten electrodes should always be ground in the longitudinal direction. A grinding of the electrodes in the circumferential direction can scatter the arc and thus negatively affect the appearance of the seam. Diamond grinding wheels should be used for grinding in order to keep the surface roughness as low as possible as this could deflect the arc. Inhaling or distributing grinding dust should be avoided - especially with electrodes with thorium dioxide (suitable air extraction in the area of ​​the grinding point, wet grinding ...).

Individual evidence

  1. ↑ Handling of thorium oxide-containing tungsten electrodes in tungsten inert gas welding Website of the DGUv. Retrieved June 26, 2020.