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Practical TIG Welding: Tungsten

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00:00 - The tungsten is one of the most important items in our TIG welding process as it passes the current from our torch onto our workpiece in the form of an arc, creating the required heat to form the molten weld pool.
00:13 Tungsten is a metal that has an extremely high melting temperature of over 3000°C.
00:18 When used for TIG welding, the tungsten is usually alloyed with other elements to improve this melting point as well as the life expectancy of the electrode and also adding other characteristics that are beneficial for its use in TIG welding.
00:33 Tungsten electrodes are a consumable in the welding process and as such, they're sold in packs and come in 3 different diameters.
00:42 The most commonly used being 2.4 mm but you can also go smaller at 1.6 mm and larger at 3.2 mm.
00:51 The diameter of the tungsten dictates the peak amount of amperage that it can handle.
00:55 So a 1.6 mm diameter tungsten is stable up to around 150 amps while a 2.4 mm will support 220 amps and the 3.2 mm is designed for heavy industrial use at amperage levels that range in excess of 300 amps.
01:13 Having 3 size variations can be a little bit confusing when deciding on what tungsten to use but in motorsport fabrication, it's common to only need the 2.4 mm tungsten for all material thicknesses at amperage levels up to 220 amps.
01:30 In the past, we've had the choice between different tungsten that had been alloyed with various elements to produce a welding electrode that's better suited to a specific material.
01:40 These are colour coded and will have varying amounts of elements like cerium and lanthenum which reduce burn off, thorium which assists in a smooth start and reduced burn back and zirconium which improves arc stability and also reduces burn back.
01:56 It's been common for example to use 2% thoriated tungsten which is distinguished by a red marking, for use when DC welding, while white tungsten which is alloyed with zirconium and grey tungsten which is alloyed with cerium, are better suited to AC welding on alloy materials.
02:13 Zirconiated tungsten for example retains a bald tip and has a high resistance to contamination which has traditionally been ideal for AC welding.
02:23 With that said, a bald tip has become less critical in recent years with today's modern machines that feature balance control, but we'll get into this in more detail later.
02:33 It's becoming increasingly difficult though to source thoriated tungsten due to the fact that thorium is radioactive.
02:42 The reality is that studies have concluded the risk of using thoriated tungsten for welding is so low as to be almost insignificant, providing some sensible precautions are taken when sharpening the tungsten due to the radioactive dust produced during this process.
02:59 Many welders still swear by thoriated tungsten DC welding, stating that they last the longest, hold the sharpest tip and produce the strongest arc.
03:08 It's reasonable to assume that with increased concerns over liability, red tungsten is likely to become only harder to source but fortunately we do have alternatives available.
03:20 These are referred to as multi mix tungsten and they're identified by a pink, blue or gold colour depending on the exact elements that the tungsten's been alloyed with.
03:30 Depending on where you are in the world, this may also define what specific colour multi mix tungsten you have access to but for all intents and purposes, they're interchangeable.
03:41 These electrodes are safe to use and are a great performer for both AC and DC welding, meaning you don't have to switch tungsten as you swap back and forth between different materials.
03:52 With recent advancements in inverter technology, the arc profile that jumps off our tungsten electrode to the workpiece is going to be strong and stable but the shape of this arc is actually determined by how we sharpen the tungsten and we'll cover this sharpening process in detail in an upcoming module but for now, just understand that it relates to the angle and the direction we sharpen the electrode for use.
04:16 Depending on the required length of your back cap on the TIG torch, you may also need to cut your 180 mm long tungsten down before you can use it.
04:26 By cutting the tungsten in half, you'll find that it'll fit nicely in the torch using a short back cap to keep the entire torch assembly nice and compact.
04:35 This will give you more flexibility, allowing you to fit the torch into compact tight areas.
04:41 You need to be careful though as tungsten electrodes are extremely brittle and this makes halving them a little difficult and any bending may actually cause the electrode to split lengthways.
04:52 Don't stress too much about this for now though, we'll be tackling all the preparation work in much more detail in its own module soon.
04:59 So to sum up this module, we've learned that tungsten is a metal with an extremely high melting temperature, which makes it ideal as an electrode material.
05:08 The diameter of the tungsten dictates the peak amount of amperage it can handle so make sure you have an idea of what you're going to be working with before shopping around, although with that said, 2.4 mm tungsten will cover almost everything we'll be doing in motorsport fabrication.
05:25 Although there are plenty of different options and they're all colour coded.
05:28 In most cases you'll be best to start out by using multi mix tungsten which is suitable irrespective of the material that you're welding.

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