What is the correct gas for MIG welding?

argon
The basic gas for MIG/MAG welding is argon (Ar). Helium (He) can be added to increase penetration and fluidity of the weld pool. Argon or argon/helium mixtures can be used for welding all grades.

What is a shield gas in welding?

Shielding gases are inert or semi-inert gases that are commonly used in several welding processes, most notably gas metal arc welding and gas tungsten arc welding (GMAW and GTAW, more popularly known as MIG (Metal Inert Gas) and TIG (Tungsten Inert Gas), respectively).

What is an active gas in welding?

Active shielding gases used for the welding of steels are carbon dioxide or mixtures of argon, carbon dioxide and oxygen. Examples of these active gases include CO2 , Ar + 2 to 5\% O2 , Ar + 5 to 25\% CO2 and Ar + CO2 + O2. Gases for other materials may include hydrogen, nitrogen or other specialised gases.

Why is purging necessary?

Purging ensures that you have control over which gases are in your gas delivery system, and therefore which gases are being exposed to internal components, sensors, or other equipment. It also helps to prevent unwanted reactions from taking place, which can greatly increase the service life of related components.

Why is purging needed in SS welding?

Why should you use Inert Gas Purging when welding Stainless Steel, Titanium and Nickel Alloys? Preventing oxidation and thus avoiding discolouration and weld underbead discontinuities in tubes and pipes can be achieved readily by purging the inside with inert gas.

What is the difference between inert and active gas?

Capability of altering properties of weld bead: Inert shielding gases remain stable during welding and thus do not induce any chemical elements on weld bead. However, active gases can break down under extreme arc temperature and can subsequently induce relevant chemical elements on weld bead.