What Does the Color of a Tungsten Electrode Mean?
This time we will look a little deeper into TIG welding, a welding process that uses tungsten electrodes and depends on the hardness of the tungsten and the resistance to high temperatures to transfer the welding current to the welding arc.
But there is more than one tungsten electrode, they are distinguished by their colors. The most common electrode colors you will see are:
1. Green color code
The green color code indicates a pure tungsten electrode containing 99,59 % tungsten. These electrodes are usually used for DC welding as they do not provide a strong arc. In the case of AC welding, they provide high arc stability.
2. Red color code
Tungsten electrodes with a red color code contain 97,30 % tungsten and up to 2,20 % thorium. As this electrode operates below the melting temperature, it ensures much slower abrasion. It is the latter which makes them one of the most widely used in this process and they are used for welding thin sheet metal.
3. Gold color code
In this case, we are referring to electrodes known to the welding public as 1,5 % lanthanum electrodes. This is due to the fact that they contain up to 1,70 % lanthanum in addition to a minimum of 97,80 % tungsten. In specific characteristics they are quite close to both cerium and thorium electrodes. Another major feature of these electrodes is that, compared with pure tungsten electrodes, the maximum conductivity of the electric current can be increased by about 50 % for a given electrode size.
4. Gray color code
Grey electrodes are tungsten electrodes containing unspecified additions of rare metal oxides. The manufacturer of these electrodes shall clearly indicate each individual additive on the packaging.
5. Orange color code
These tungsten electrodes also contain at least 97,30 % tungsten, with up to 2,20 % cerium added. They are used for welding thinner and more sensitive parts, but are in principle very similar to those tungsten electrodes with thorium, i.e. with a red color code.
6. Blue color code
Blue tungsten electrodes contain 98 % tungsten and 2 % lanthanum oxide and give very similar results to red color coded tungsten electrodes. They are characterized by their easy and fast arc ignition and long lifetime. They are used for welding high and low alloy steels, aluminium, magnesium, copper, nickel and titanium.
What is TIG welding anyway?
TIG welding (T – Tungsten / I – inert / G – gas) involves welding with a non-fusible tungsten electrode in an inert gas such as argon, helium or similar. It is used for welding thin stainless steel, but also for joining aluminium, magnesium and copper alloys.
TIG welding is used by more skilled welders and is mainly used in the aerospace industry, but also for welding thin-walled tubes of smaller diameters.