What is the most commonly used shielding gas in TIG welding?

The most commonly used shielding gas in TIG welding is argon. This gas is favored because it is inert, which means it does not react chemically with the molten weld pool or the base metals being welded. Argon provides excellent coverage, preventing contamination from atmospheric elements, which can cause defects such as porosity in the weld.

Additionally, argon has a lower ionization potential than helium, resulting in a more stable arc and making it easier to control the welding process, especially for thin materials. Its accessibility and cost-effectiveness compared to other gases further contribute to its widespread use in TIG welding applications.

While helium is also used as a shielding gas, particularly for specific applications requiring higher heat input, it is not as commonly utilized as argon. Other gases like carbon dioxide and oxygen are typically unsuitable for TIG welding, as they can react with the molten metal and lead to undesirable qualities in the weld.