TUNGSTEN

TUNGSTEN

The nuts and bolts for best welding results.

For tungsten inert gas welding (TIG), the non-fusing and temperature resistant tungsten electrode, in addition to the torch, the energy source and the inert gas, is a major factor for obtaining optimum results.


The following must be taken into consideration when selecting the tungsten electrode:

  • Type of tungsten electrode
  • Diameter of electrode
  • Quality of the polished section and roughness of the electrode
  • Tip geometry of the electrode


Influence of doping on the characteristics of the electrode.

WP

Undoped electrodes – consist of pure tungsten. The main area of application for this type of electrode is the AC welding of aluminum alloys with excellent arc stability. The WP-electrodes are not suitable for DC welding.
Colour-coding: WP = green
 

WT 10 / 20 40

Electrodes with thorium oxide (ThO2). On these electrodes, compared to pure tungsten, the work function is reduced due to the doping (same as with oxides of rare earth), i.e. during the operation the emission current density of the electrodes is increased while the temperature is kept the same. With increased thorium doping, service life, ampacity and refiring properties improve. The main area of application for these electrodes is the DC welding of high-alloyed and stainless steel.
Colour-coding: WT 10 = Yellow / WT 20 = Red / WT 40 = Orange

Caution! Thorium is a naturally radioactive element. Its decomposition products are also radioactive. Therefore, the use of tungsten electrodes with thorium oxide (ThO2) should consequently be avoided, if at all possible. If thoriated electrodes are used anyway, make absolutely sure an extraction system is in place when grinding down the electrodes - only suction devices of the dust grade H (highest dust grade) are approved - and also for optimum weld fume extraction. This is because the main risk potential of thoriated electrodes lies in the alpha rays when radioactive particles are inhaled which will remain in the lungs forever and thus lead to permanent damage to the cells, and perhaps even lung cancer. The gamma rays on the other hand are almost negligible. See also BGI 746; dealing with thorium-oxide containing tungsten electrodes during tungsten inert gas welding.

 

 

WR 2

 

Electrodes with rare earth (mixed oxides). The non-radioactive electrodes that are free of thorium offer excellent firing and consistent welding properties. These are used specifically in the lower and medium ampere range for steel, stainless steel, copper and brass applications. Because of their firing properties they are preferred for automatic welding.
Colour-coding: WR 2 = Turquoise

 

WL 10 / 15 / 20

 

The lanthanated electrodes are universal and may be used for nearly all applications in DC and AC welding. The main areas of application are the welding of unalloyed and high-alloyed steel, aluminum, titanium, nickel, copper and magnesium alloys. Another area of application for these electrodes is micro-plasma welding.
The ignitability of the electrodes is enhanced with the increased content of lanthanum oxide (La2O3). This proves to be a big advantage during automatic welding.
Colour-coding: WL 10 = Black / WL 15 = Gold / WL 20 = Blue
 

WC 20

The universal electrode for just about all applications. By adding ceroxide (CeO2) these electrodes have a similar effect as the electrodes with thorium oxide (ThO2). Compared to the thoriated electrodes, the electrode with ceroxide (CeO2) is less harmful to the environment and not radioactive. The main area of application for these electrodes is the DC and AC welding of unalloyed and high alloyed steel, aluminum, titanium, nickel, copper and magnesium alloys.
The electrodes offer excellent firing properties, also for refiring of warm electrodes. Furthermore, they convince with their long service life and excellent ampacity.
Colour-coding: WC 20 = Grey
 

WZ 08

Tungsten electrodes with the addition of zirconium have a lower risk of contaminating fused materials from the tungsten. The area of application for this electrode is AC welding. They are suitable for DC welding to only a limited extent.
Colour-coding: WZ 08 = White