Several factors will influence TIG welding and how well it turns out. One of that is the equipment used. Tungsten electrodes are some of the tools you will need for TIG welding. The material tungsten is preferable because of its hardness and its resistance to high temperatures. Tungsten can withstand temperatures of up 3,410° C, which makes it suitable for arc welding. Welders have several choices nowadays when picking tungsten electrodes. When making this decision, a welder has to consider the type of current used, whether AC or DC, the thickness of the base material and how the electrodes are prepared. Tungsten electrodes come in colour codes to make it easier for welders to pick the right ones. Here is a look at some common choices and their colour codes.
Rare-earth tungsten material comes with various additives such as rare-earth or hybrid combinations of oxides. How the electrodes perform will depend on these additives. In some cases, the electrodes may provide a more stable arc compared to other tungsten materials. Another benefit of rare-earth tungsten electrodes is that a welder can have them in small diameters, and they will still provide good service. There is also less tungsten splitting when using the electrodes. Compared to thoriated tungsten, this type of electrode lasts longer.
For starters, pure tungsten is suitable for use with AC but not DC. Pure tungsten electrodes are 99.5% tungsten, and that gives them the capability to ball easily. The ball tip shape is what makes the electrodes good with arc stability. Pure tungsten is also suitable for application of low to medium amperages with magnesium and aluminium alloys.
Lanthanated tungsten electrodes are suitable for use with direct current. Or transformer-based constant current power sources. They contain 97.8% tungsten and between 1.3 and 1.7% lanthanum. These electrodes are said to be 1.5% lanthanated. The incorporation of lanthanum adds to the capacity of the electrodes to carry current to an arc by almost 50%. Some of the traits that make this electrode a good choice include great arc starting and stability, impressive re-ignition properties and low burn-off rate. For preparations, lanthanated electrodes can be balled or with a pointed end. Welders sometimes switch between 1.5 lanthanated tungsten electrodes with 2% thoriated because they have the same properties.
The principal oxide in ceriated tungsten electrodes is cerium oxide and is present in about 1.8 to 2.2%, whereas the pure tungsten composition is at a minimum of 97.3%. These types of electrodes are called 2% ceriated and are suitable for low-current AC usage. It is also possible to use them in DC applications. Ceriated tungsten electrodes are ideal for welding small and delicate parts like in thin sheet metal work, pipe fabrication, and orbital tube manufacturing. Some of the compounds that can be used with ceriated electrodes include non-corroding steels, carbon, nickel, aluminium, magnesium, titanium and copper alloys. Properties include longevity, excellent arc stability, low erosion rate, good ignition and re-ignition. They should be used at low amperage ranges. Welders nowadays prefer to use ceriated tungsten electrodes in place of pure tungsten because the former offers better current carrying properties at the same diameters.
Thoriated tungsten electrodes contain 97.3% pure tungsten and 1.7-2.2% thorium oxide, which has low radioactivity. The increased current carrying ability of thoriated tungsten electrodes is one reason it suits arc welding. The electrodes are easy to use and last a long time, which offers added advantages. They also provide a low consumption rate because they function below their melting point. Thoriated tungsten electrodes are suitable for both AC and DC applications. They are ideal for welding thin steel because they maintain sharpened edges during manufacturing. Caution is, however, recommended when sharpening the points of thoriated tungsten electrodes. Welders also prefer thoriated tungsten electrodes because they cause less contamination during the process. They are suitable for use in medium amperage ranges, have a medium erosion rate and tendency to split is average compared to other materials.
Zirconiated tungsten electrodes consist of 99.1% pure tungsten and 0.15-0.4 Zirconium. The ability of zirconiated electrodes to retain balled tips is what makes them perfect for AC welding. These types of electrodes don’t contaminate easily and are highly resistant to splitting. Zirconiated tungsten has high current-carrying ability resulting in an extremely stable arc. It also handles high amperages very well. Zirconiated tungsten electrodes are not suitable to use with DC.