Tungsten Electrode

What is Electrode?

An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit (e.g. a semiconductor, an electrolyte or a vacuum). The word was coined by the scientist Michael Faraday from the Greek words elektron (meaning amber, from which the word electricity is derived) and hodos, a way.

Tungsten Electrodes for TIG welding

Tungsten electrodes are used when arc welding with the Tungsten Inert gas (TIG) process or when plasma welding. In both processes the electrode, arc and weld pool are protected from atmospheric contamination by an inert gas. A tungsten electrode is used because it can withstand very high temperatures with minimal melting or erosion. Electrodes are made by powder metallurgy and are formed to size after sintering.

TIG welding electrodes usually contain small quantities of other metallic oxides which can offer the following benefits:-

  • facilitate arc starting
  • increase arc stability
  • improve current-carrying capacity of the rod.
  • reduce the risk of weld contamination
  • increase electrode life

Oxides used are primarily those of zirconium, thorium, lanthanum, yttrium or cerium. Additions are usually of order 1%-4%. All these oxides greatly improve arc initiation, especially when direct current (DC) welding is employed. Thorium oxide (thoria) has been used for many years having been found effective in terms of long life and thermal efficiency. Zirconium oxide (zirconia) has been commonly used for alternating current (AC) TIG welding, normally for welding aluminium.

Type Brand Color Chemical Composition(%) Sizes
Surface Features
Rare Earth Impurities W
WP Green ≤0.05 the rest 0.8~15 D,E
Non-radioactive;suitable for AC welding of aluminum, magnesium, and their alloy
WTh10 Yellow 0.9~1.1ThO2 ≤0.05 the rest 0.8~15 D,E
Excellent electron emission and overall performances; high current-carrying capacity; radioactivity; suitable for DC welding of carbon steel, stainless steel,nickel alloy and titanium alloy.
WTh20 Red 1.8~2.2ThO2 ≤0.05 the rest 0.8~15
WLa10 Black 0.8~1.2La2O3 ≤0.05 the rest 0.8~15 D,E
Non-radioactive;excellent electric conductivity and welding capacity; high current-carrying capacity; minimum ratio of burnt area; substitute for thoriated tungsten electrode; mainly used in DC welding.
WLa15 Golden
1.3~1.7 La2O3 ≤0.05 the rest 0.8~15
WLa20 Blue 1.8~2.2 La2O3 ≤0.05 the rest 0.8~15
WCe10 Pink 0.8~1.2CeO2 ≤0.05 the rest 0.8~15 D,E
Non-radioactive;easier arc initiation under low current circumstances, and low arc-maintaining current;suitable for the welding of pipelines,small components and discontinuous welding.
WCe15 Orange 1.3~1.7CeO2 ≤0.05 the rest 0.8~15
WCe20 Grey 1.8~2.2CeO2 ≤0.05 the rest 0.8~15
WY20 Sky
1.8~2.2Y2O3 ≤0.05 the rest 0.8~15 D,E
Non-radioactive;long and slim arc beam with high compression; deeper burning groove under medium and high current circumstances.
Rare Earth
WMX Cyan 1.0~5.0MOx ≤0.05 the rest 0.8~15 D,E
Compound rare-earth tungsten electrode; different additives contributing to better performance of tungsten electrode

Note:D—As Drawn E—Electrolytic Polished G—Ground S—Swaged

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