Shielding gases are used while TIG and MIG welding to protect your weld puddle from being exposed to oxygen, nitrogen, and hydrogen in the atmosphere. These elements can interact with the molten metal and cause defects in your weld. Shielding gases can also help with arc starting, cleaning, penetration, and arc stability. These gases play an important role on your finished product as well as your welding experience.
With so many variations to pick from, welders commonly ask what is the best shielding gas for their application? Though the answer varies depending on the base metal and process, we've compiled a shielding gas selection guide to help with your selection. Our process engineering group is also available to do a free Gas Application Analysis to ensure you are getting the best results for your end product.
As a shielding gas, argon provides the most stable arc combined with the most effective cleaning action. Argon offers welders excellent control of the welding arc and puddle.
Carbon dioxide is valuable in arc welding processes due to its high heat conductivity. Mixtures of carbon dioxide are often recommended to increase penetration of the weld.
Helium has a high voltage gradient and provides more heat than pure argon at equivalent arc lengths. Pure helium is excellent to use when the highest possible heat input is needed. Since helium is lighter and less dense than argon, two to three times as much is needed for equivalent shielding effectiveness.
Hydrogen provides high heat conductivity and reducing properties that make it a valuable shielding gas for stainless steel. It is also used to increase welding speed. Mixtures of hydrogen are often recommended to increase compatibility with certain materials.
The heat conductivity characteristics of oxygen are useful for increasing welding speed and improving material soundness, penetration, and head shape.
In order to help make gas selection easier, please see the below charts with recommended shielding gases for common applications.