Which shielding gas is commonly used when welding aluminum with GMAW?

Which shielding gas is commonly used when welding aluminum with GMAW?

• A. Helium
• B. Oxygen
• C. Nitrogen
• D. Argon

Answer: (D)

In GMAW of aluminum, the shielding gas must protect the molten pool from air and provide a stable arc. Argon is chosen because it is inert and supports good arc stability and weld bead control for aluminum. It protects the oxide layer that forms so quickly on aluminum and helps produce clean, smooth welds, especially with the common spray transfer mode and AC welding. Helium can be used in some cases, but it is more expensive and increases heat input, which isn’t the default choice. Oxygen and nitrogen would contaminate the weld, leading to porosity or other defects, so they’re not suitable shielding gases for aluminum in GMAW.

In GMAW of aluminum, the shielding gas must protect the molten pool from air and provide a stable arc. Argon is chosen because it is inert and supports good arc stability and weld bead control for aluminum. It protects the oxide layer that forms so quickly on aluminum and helps produce clean, smooth welds, especially with the common spray transfer mode and AC welding.

Helium can be used in some cases, but it is more expensive and increases heat input, which isn’t the default choice. Oxygen and nitrogen would contaminate the weld, leading to porosity or other defects, so they’re not suitable shielding gases for aluminum in GMAW.