 When it comes to TIG welding, the most commonly asked question is “What tungsten do I use?” As we know, welding equipment is constantly evolving. At one point in history, the most commonly used power source was known as a rectifier machine. Today, equipment is more commonly inverter based, which gives the welder more control of the arc. There are a few things you must determine before selecting a tungsten electrode such as:
Metals such as carbon steel, stainless steel, titanium, chromoly, brass, and copper will be welded using Direct Current with the electrode negative. Generally, aluminum alloys are welded using Alternating Current (AC). Pure tungsten (green stripe), for years was the best choice for AC welding, but with the industry shift to invert based machines, with advanced squarewave technology, rare earth tungsten such as Ceriated (gray stripe) and Zirconiated (brown stripe) are an option. The most commonly used electrodes today are 2% Thoriated (red stripe). Thorium has great arc start characteristics and allows for higher current carrying capacity. Although, if thoriated tungsten is used in the AC mode, the tungsten tends to split and get nodules around the electrode instead of a nice round ball. In return, this gives you an unstable arc and inconsistent heat input. It can also cause tungsten spitting giving you impurities in your weld. Also, choosing the proper grind angle, constant current range or pulsed current range will affect the electrode current range. Example .040 has range from 2 to 60 amps, .093 has range from 12 to 250 amps and .125 has range from 20 to 350 amps. tungsten selection chart |
| Type of Tungsten Pure Ceriated Thoriated 1.7 to 2.2% Lanthanated 1.3 to 1.7% Zirconiated .15 to .40% | Color Code Green Gray Red, Yellow Gold, Black, Blue Brown | Remarks Good arc stability for AC. Least expensive. Easy arc starts, and long life. Replacement for thoriated. Higher current capacity, greater arc stability, difficult to maintain balled end on AC. Easy arc starts, high current carrying capacity, similar to thoriated. Excellent for AC, good arc starting, limited contamination of weld. |
Daryl Kehr
Account Manager at Earlbeck Gases & Technologies
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