The gas in orbital TIG welding protects the weld puddle and the metal transferred into the welding arc from the ambient air.
This can seem strange as oxygen, hydrogen or nitrogen are sometimes added intentionally to the shielding gases in order to increase the energy input, the visual appearance of the weld bead or the quest for specific metallurgical characteristics.
These gas mixtures are only used if the added gas does not have any negative metallurgical effect on the material.
Fostering the formation and stability of the arc
The gas must foster the formation and the stability of the arc. It plays an important role in creating ideal welding conditions of the electric arc, especially:
- in order to facilitate the striking of the arc
- can be easily ionized for creating a low tension arc
- to obtain a stable arc at the root
- to influence the reaction of the weld puddle (wettability, fluidity, penetration)
- to contribute to the heat transfer
- to guarantee weld bead profile
It's important to remember that you need to master all the stages to have a perfect weld!
The direct influence of the gas in orbital welding
The shielding gas has a direct influence concerning several elements in orbital welding:
- the stability of the arc
- the mechanical characteristics
- the seam geometry
- the appearance of the weld bead
- the welding speed
- the workplace environment
- the energy input
As you can see, the gas plays an important role regarding the final quality of a TIG welding result. Don't hesitate to download our free handbook to learn more about shielding gases in TIG welding!