GMAW Shielding Gases

Understanding shielding gas selection is an important part of welding quality.

In GMAW (Gas Metal Arc Welding), the shielding gas depends mainly on the welding process and base material.

♦ MIG – Metal Inert Gas

Uses inert gases such as:

※ 100% Argon (Ar) – Aluminium and non-ferrous alloys

※  Helium (He) – Aluminium and other non-ferrous applications

※  Ar + He mixtures – Aluminium and copper alloys

♦ MAG – Metal Active Gas

Uses active gases such as:

※ 100% CO₂ – Mainly carbon steel

※ Ar + CO₂ – Carbon steel and low-alloy steel

※ Ar + O₂ – Mainly carbon and low-alloy steels

» Typical Material Selection

※ Aluminium → MIG → Argon / Argon + Helium

※ Carbon Steel → MAG → Ar + CO₂ / CO₂

※ Stainless Steel → MAG → Ar + CO₂ or Ar + O₂ (depending on grade and application)

» Key point:

MIG = inert shielding gas

MAG = active shielding gas

◊ Gas composition should always be selected according to the WPS, material grade, welding transfer mode and applicable code/standard.