Practical tips for welding: tungsten electrodes

Posted by Richard Baumann on Oct 22, 2020 1:39:21 PM
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All about the welding accessories TIG welding electrodes

Finely crafted weld seams, clean welded joints, high-quality materials – welcome to the world of TIG welding and tungsten electrodes. Choosing the right tungsten electrode is just as important for TIG welding as the contact tip for MAG welding. The range of TIG welding electrodes on the market is just as colorful as the color coding that characterizes each individual type of tungsten electrode. In this blog post we would like to give you a good overview of the essential tungsten electrodes to make it easier for you to choose if you want to buy them.

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Tungsten electrodes and their doping

Tungsten is the main component of TIG welding electrodes, but apart from the pure tungsten electrode (WP green), all others are enriched with further elements, which is known as doping. This is also called tungsten doping.

 

But which tungsten electrode is the right one for my welding process?

 

The selection of the right tungsten electrode or its doping depends largely on the welding task: whether you want to weld direct current or alternating current, the choice of electrodes is limited, because not every type is also suitable for alternating current, which for example is used for aluminum welding. Depending on the type of current, the welding task and the material to be welded, pure tungsten electrodes are used or those with oxidic additives, usually consisting of rare earths. These additives are zirconium oxide (ZrO2), lanthanum oxide (La2O3), cerium oxide (CeO2) or thorium oxide (ThO2) – and they all have different properties.

 

The doping elements and their effect:

  • Compared to pure tungsten electrodes, zirconium oxide keeps the evaporation lower and enables a more stable arc.
  • Lanthanum oxide has particularly good ignition properties and gives the electrodes a longer service life.
  • Cerium oxide gives a tungsten electrode very good ignition and reignition properties.
  • Thorium oxide creates a very stable arc, but due to its radioactivity it is very harmful to health and as an additive to tungsten electrodes is now banned in many countries. Once thorium smoke or dust is inhaled, it can be deposited in the lungs and lead to internal radiation exposure.

The pure tungsten electrode (WP green) enables a very steady arc. Oxide-containing electrodes, on the other hand, are easier to ignite, have a high current carrying capacity and a longer service life.

 

So it is obvious that the choice of the right TIG welding electrode for a welding task largely depends on what you focus on in TIG welding.

 

The tungsten electrode table shown below gives you an overview of the most common types and their suitability and properties. Do you mainly weld high-alloy steels or aluminum? Is the service life of the electrode more important to you or its ignitability? With this table you can make your pre-selection much easier.

 

Table tungsten electrode selection

 

E3®

purple

WLa 15

gold

WLa 20

blue

WCe 20

grey

WP

green

WZr 08

white

DC negative

+++

++

+++

+

-

-

Alternating current

+++

+

+

+

+

++

Arc stability

++

+

++

+

-

++

Ignitability

++++

++

+++

+

-

+

Service life

++++

++

+++ + + ++

High-alloy steels suitability

++++

+++

+++ +++ - -

Aluminium suitability

++++

+

+ + ++ ++

 

Tungsten electrode colors and their application

E3®

Let’s start with the best: The E3® is a tungsten electrode developed by ABICOR BINZEL with a mixture of rare earth oxides as doping elements, which is suitable for both direct current and alternating current welding and practically every metal. It has excellent ignition properties and is therefore also often used for automated processes. The electrode temperature remains consistently low, which in turn increases the current-carrying capacity and the service life compared to thoriated electrodes – which are only allowed to be used in exceptional cases because of their extremely harmful effects.

 

Color coding with a mixture of rare earth oxides is:

Purple = E3®

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WLa

Like the E3®, this tungsten electrode with the doping element lanthanum oxide, can be used for direct current and alternating current welding. It is mainly used for welding unalloyed and high-alloy steels, aluminum, titanium, copper and magnesium alloys. The golden tungsten electrode is also used in micro-plasma welding.

 

Color codings with lanthanum oxide are:

Gold = WLa 15 – with 1.30 to 1.70 % lanthanum oxide

Black = WLa 10 – with 0.80 to 1.20 % lanthanum oxide

Blue = WLa 20 – with 1.70 to 2.20 % lanthanum oxide

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WCe

Due to the component of cerium oxide, this TIG welding electrode is more resilient than one with pure tungsten – but less than the E3® and lanthanum electrodes. This type of tungsten electrode is mainly used in the medium and lower current range for welding unalloyed and high-alloy steels as well as aluminum, copper, nickel, titanium and magnesium alloys. They are also suitable for alternating current welding as well as for direct current welding, but not as well as the E3® electrodes from ABICOR BINZEL.

 

Color coding with cerium oxide is:

Grey = WCe 20 – with 1.80 to 2.20 % cerium oxide

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WP

This TIG welding electrode is made of pure tungsten and is used exclusively for AC welding. In this application it is the ideal electrode for welding aluminum alloys, as its melting point of 3,422 °C is ideally high for welding with alternating current. Tungsten also has high resistance and very high corrosion resistance.

 

Color coding with pure tungsten is:

Green = W – made of pure tungsten without any oxide component

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WZr

The addition of zirconium oxide means that the risk of contaminating the fusion is very low. This tungsten electrode was specially developed for welding with alternating current in nuclear systems. Zirconium oxide ensures a very stable spherical cap in AC welding, but it ignites very modestly in DC welding.

 

Color codings with zirconium oxide are:

Brown = WZr 03 – with 0.15 to 0.50 % zirconium oxide

White = WZr 08 – with 0.70 to 0.90 % zirconium oxide

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Tip:

The WZr and the pure tungsten electrode should only be used with the old single-phase TIG power sources.

 

Hands off tungsten electrodes with thorium!

TIG welding electrodes with thorium oxide as a doping element are extremely harmful to health due to their radioactive properties and are now banned in several countries. The German statutory accident insurance »DGUV« information 208-049 refers to the fact that thorium oxide-containing tungsten electrodes according to Section 4.2 (1) of TRGS 528 “may only be used for product-specific requirements (compelling technical reasons)” and that the provisions of the Radiation Protection Ordinance must be observed. So hands off tungsten electrodes with thorium!

 

Is there a type of TIG welding electrode that can be used for any welding task?

Yes, there is: E3® (purple). This tungsten electrode is a long-lasting TIG welding electrode that guarantees the best results. It is not only a better alternative to other electrodes for the welder and his health, but also for the environment. Grinding dust, filter dust and leftover pieces are not hazardous waste, and transport and storage do not require any special protective measures because the E3® welding electrodes are absolutely free of radioactive components.

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The E3® tungsten electrodes comply with the EN ISO 6848 standard and, like all TIG welding electrodes from the ABICOR BINZEL product portfolio, are manufactured in our own production network and are characterized by the highest product quality. Each packaging of our E3® tungsten electrodes has a batch number, which guarantees traceability if necessary. Upon request, you can also receive a production certificate and a safety data sheet. Please feel free to contact us.

 

The advantages of the E3® welding electrodes at a glance:

  • »Cool« electrode tip
  • Excellent ignition and re-ignition properties
  • High arc stability
  • Low burn-off
  • High current carrying capacity
  • Little deformation of the electrode tip
  • Suitable for practically all welding tasks

 

If you want to be on the safe side when choosing your welding electrode for TIG welding and the quality of the weld seam is important to you, you should definitely test the E3® tungsten electrode from ABICOR BINZEL. Have you already welded with the E3®? Then you are welcome to share your experiences with us.

 

Happy welding!