What Is … TIG Welding?

TIG arc between tungsten electrode and workpiece

What does “TIG” stand for? Why is inert gas used in this process? And what role do tungsten electrodes play? Welding is complex but the basics are actually pretty easy to understand. The Fronius “What is …?” series helps to build an understanding of welding and to maintain an overview of the basic terms.


Tungsten Inert Gas Welding

TIG welding is a process that enables top-quality weld seams. The arc burns between a temperature-resistant, non-melting tungsten electrode, and the workpiece. The inert shielding gas that gives the process its name creates an oxygen-free gas atmosphere and prevents chemical reactions with the liquid weld pool. This results in smooth, level, and non-porous weld seams. The filler metal is guided manually or using a wirefeeder.


TIG welding diagram

TIG welding can be used for all metals that are suitable for welding. The biggest area of application here is stainless steels, and the processing of non-ferrous metals such as aluminum, copper, and brass. TIG is primarily used for root passes as the seams are smooth and non-porous, and can therefore withstand dynamic forces well.


Inert Shielding Gas

For TIG welding, reaction-free (inert) shielding gas is used. The gas atmosphere has a protective function, preventing chemical reactions with the liquid weld pool and the heated material. This guarantees high-quality weld seams.

The noble gases argon and helium, or a mixture of these gases, are used as shielding gases. Argon is used most frequently as it provides optimal conditions for ignition and ensures a particularly stable arc. Helium conducts heat more efficiently than argon and therefore ensures deep and wide penetration.


Tungsten ElectrodesTIG arc between tungsten electrode and workpiece

The tungsten electrode is at the core of TIG welding. At 3380 degrees Celsius, tungsten has the highest melting point of any pure metal in the periodic table. This means the electrode can emit an arc that heats and liquefies the workpiece without itself melting away.

The electrodes are produced using a sintering process. They can also be alloyed using oxidic additives to improve their properties. The electrodes are color-coded according to the alloy used:

Tungsten/Lanthanum Oxide Electrodes
Tungsten/lanthanum oxide electrodes are colored blue
  • Pure tungsten (WP) (green):
    Flat, spherical electrode surface
    Ignition problems with DC
    Low current-carrying capacity
  • Thorium oxide (WT 20) (red):
    Excellent ignition properties
    Significantly higher current-carrying capacity than pure tungsten electrodes
    Slightly radioactive (alpha emitters)
  • Cerium oxide (WC 20) (gray):
    Similar properties to thorium
  • Lanthanum oxide (WL 20) (blue):
    Longer service life than tungsten/thorium or tungsten/cerium oxide electrodes
    Poorer ignition properties


High Frequency Ignition

One particular characteristic of TIG is that the arc can be ignited without contact. A series of fast high-voltage pulses cause a spark to jump across to the workpiece and the arc then stabilizes itself. High frequency ignition is extremely easy for the welder to handle. The electrode cannot stick to the workpiece, is not contaminated, and no tungsten inclusions are created in the seam.


You can read more about the advantages of the TIG process in the Fronius blog article “TIG Welding: Top-Quality Connections.”



Join the discussion and tell us your opinion.

Jerald Fernandesreply
22. May 2018 at 17:32

Very nice to read these basics. Helps a lot

23. May 2018 at 6:46
– In reply to: Jerald Fernandes

Thank you! Great to hear that!

18. June 2018 at 17:45

Very helpful videos thank you

19. March 2019 at 7:16
– In reply to: EARL LOWERY

Thank you!

Nathan Martinreply
16. March 2019 at 11:33

I’m glad you shared this helpful information with us. Please keep us up to date like this. This is actually a good and useful piece of information. thank you for sharing.

19. March 2019 at 7:17
– In reply to: Nathan Martin

Thank you for your nice feedback! Glad you like these kind of blog posts!

James Johnsonreply
14. September 2019 at 2:43

Very helpful information. But we must focus on our safely first. Anyway thanks for sharing. Keep it up.

13. July 2020 at 8:38
– In reply to: James Johnson

Thank you for your feedback!

Oliver TIGreply
11. July 2020 at 16:14

It is awesome to get to know about all the basics of Tig welding. Being a novice in this field i am highly thankful.

13. July 2020 at 8:38
– In reply to: Oliver TIG

Thank you very much!

11. September 2020 at 14:46

You have explained tig welding in a very clear way.
I am a newbie and I hope i will improve my skills with it. Good work!

14. September 2020 at 7:40
– In reply to: jason

Thank you very much for your feedback!

30. September 2020 at 10:38

Great explanation by you. it really helps beginners like me. Impressed by your work and hope you will definitely work like this in the future.
God bless you.

15. October 2020 at 9:20
– In reply to: Jimmy

Dear Jimmy, we are happy to hear that you like this blog article. We are trying to do our best to keep it up – for example with our basics article about MIG/MAG welding or about how to correctly apply the welding settings. I hope those are helpful too 🙂

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