Colour codes for tungsten electrodes

The electrode used in GTAW is made of tungsten or a tungsten alloy, because tungsten has the highest melting temperature among pure metals, at 3,422 °C (6,192 °F).

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As a result, the electrode is not consumed during welding, though some erosion (called burn-off) can occur. Electrodes can have either a clean finish or a ground finish—clean finish electrodes have been chemically cleaned, while ground finish electrodes have been ground to a uniform size and have a polished surface, making them optimal for heat conduction.

The diameter of the electrode can vary between 0.5 and 6.4 millimetres (0.02 and 0.25 in), and their length can range from 75 to 610 millimetres (3.0 to 24.0 in).

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Reference: Gas tungsten arc welding

Non-Consumable Electrode Features

  1. Pure Tungsten:
  • Color Code – Green
  • AWS Classification – EWP
  • 99.50 % Tungsten
  • Ideal for AC welding
  • Excellent arc stability
  • Less expensive
  1. Thoriated:
  • Color Code: Red
  • AWS Classification – EWTh-2
  • Tungsten (97.30% min.) + Thorium (1.70% to 2.20%)
  • Also known as 2 percent thorium
  • Preferred for longevity and ease of use
  • Can be used with both AC as well as DC
  • Expensive and radioactive material
  1. Ceriated:
  • Color Code: Orange
  • AWS Classification – EWCe-2
  • Tungsten (97.30% min.) + Cerium (1.80% to 2.20%)
  • Also known as 2 percent ceriated
  • Preferably used with DC welding
  1. Lanthanated:
  • Color Code: Gold
  • AWS Classification – EWLa-1.5
  • Tungsten (97.80% min.) + Lanthanum (1.30% to 1.70%)
  • Also known as 1.5 percent lanthanated
  • Arc initiation excellent and very stable
  • General purpose can be used for carbon steel and stainless steel
  • Can be used with both AC and DC
  1. Zirconiated:
  • Color Code: Brown
  • AWS Classification – EWZr-1
  • Tungsten (99.10% min.) + Zirconium (0.15% to 0.40%)
  • Also known as 2 percent Zirconiated
  • Suitable for AC welding
  1. Rare Earth:
  • Color Code: Gray
  • AWS Classification – EWG
  • Contains additives of rare-earth oxides (% unspecified)
  • Polarity depends upon the percentage of the rare earth oxides
  • Wide range of applications
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