Hydrogen shielding gas usage in GMAW: which statement is correct?

Hydrogen shielding gas usage in GMAW: which statement is correct?

• A. Depends on alloy
• B. True
• C. Not used
• D. False

Answer: (D)

Hydrogen is not used as a standard shielding gas in GMAW. The shielding gas in MIG welding is chosen to protect the weld pool from contamination and to control arc characteristics, with common options like argon, helium, carbon dioxide, or blends such as argon/CO2 or argon/oxygen depending on the material and transfer mode. Hydrogen in shielding gas can diffuse into the weld metal and promote porosity and hydrogen-induced cracking, especially in carbon and high-strength steels, and it also introduces safety and handling concerns. Because of these issues, the idea that hydrogen shielding gas usage is routinely correct is not accurate, making the statement false.