GTAW Process: Tungsten Selection

TIG welding of course could not exist without the "T" in TIG. The "T" stands for tungsten. The tungsten is a small shaft of elemental tungsten used as a semi-permanent electrode to produce an electrical arc between the tungsten tip and the metal. Though considered a consumable, it does not consume at a rapid pace as in MIG or Stick welding. However, they will wear rapidly in hands of inexperienced users, through overheating, and constant immersion or “dipping” into the molten weld pool. Tungsten can be offered as pure tungsten or combined with some other element to exhibit different welding characteristics. Along with each element, varying percentages of the secondary element can be offered. Each Tungsten with its own percentage of alloying metal carries its own color marking on the Tip, and is commonly referred to the color instead the actual components and percents. However, there are some variations in color from country to country. Much of today’s tungsten is imported, and different colors than the standard color can be expected. Green tungsten is referred to as “pure” tungsten. Pure tungsten is traditionally used only with AC welding. However, with todays high performance inverter welder machines such as the Everlast Power Tig series welders, pure tungsten is a very poor choice. It will not last long and exhibits poor arc stability. Many websites and texts still recommend green tungsten for welding aluminum, borrowing recommendations from material written up to 50 years ago. This old information is confusing to many old and new welders, especially when the pure tungsten just melts away when it is stuck in an inverter machine. It’s still suitable for welding with transformer based welders, and is welded with a fairly large molten ball forming hanging on the end. It will not allow the pinpoint arc precision as some other tungstens, since the ball does not focus the arc and is subject to wander around the ball if proper technique is not used.

Thoriated Tungsten (2%) has been the standard for the welding industry in the United States for DC welding. Again, things have changed with the advent of inverter TIG welding systems. Commonly referred to as “Red” tungsten, it has excellent arc starting and overall welding capabilities. It can be used for AC or DC welding with inverter machines, such as the Everlast Power Tig 250EX. But it’s not the best choice for AC welding in transformer machine however, though it can be done. It can be sharpened to a fairly sharp point, and does not have to be balled while AC TIG welding aluminum. However, if overheated, it can split and form nodules on the side of the tungsten, creating a destabilized arc. One drawback of the thoriated, is that it is slightly radioactive. However, the radiation exposure is small compared to some other daily forms of radiation that exist. As long as the tungsten grinding dust is not breathed in, little risk, even while handling exists. Some foreign countries frown upon the use of Thoriated tungsten for its radioactivity. However, the risk does seem to be low as proven by many years of use in the industry. Overall, it probably offers the best performance for the price with a higher amp tolerance level for any given diameter. Ceriated Tungsten (2%) has been recommended by major manufacturers of welding machines as an acceptable alternative to Thoriated tungsten for users of inverter welders. It has good low amp performance, with easy arc starts at low amp levels. However, the Orange tungsten is quite expensive compared to the Red. Some people swear by it and its performance. Others are not quite sure. Testing of Ceriated tungsten has shown that there may be some deficiency when compared to Lanthanated Tungsten. But there seems to be some strong opposition to that from people who regularly use Ceriated. Keep in mind it may be difficult to find at the local welding supply store. Many online sources have it so be sure to shop around as the price and quality varies greatly. Lanthanated Tungsten is popular in 1.5% and 2%. Testing of both has shown that having more is not necessarily better. Lanthanated 1.5% is marked with a Gold paint, and Lanthanated 2% is marked with blue. Both have found considerable favor in the industry with many preferring the 2%. Many Everlast customers, who prefer not to use Thoriated tungsten have reported that this seems to work better for them than Ceriated. It seems to be found in more local locations than Ceriated. Price is slightly lower than ceriated overall. Other types of tungsten are available, of course, and with the race to be newer and better, there have been unique blends with custom names t. Zirconiated has been promoted for AC use in transformer machines, but no real benefit is achieved for inverters. Custom tri blends have been recently promoted by a few companies, and sell at a premium price. However, they have not been around long enough to gain wide spread acceptance. Whether or not these actually provide a improvement remains to be seen, whether they perform all around better or not.

Comments

Thanks for describing TIG in details....... I also hear that TIG is very hard for the newbie....... once you learn TIG welding, you know lots of thing about welding....... and TIG welding is good for most of the welding tasks. Is it correct?