Which gas mixture is used for short-circuit transfer on carbon steels and low-alloy steels?

• A. 100% Argon
• B. 100% CO2
• C. 75% Argon / 25% CO2
• D. 95% Argon / 5% Oxygen

Answer: (C)

Short-circuit transfer on carbon steels and low-alloy steels benefits from a shielding gas that provides arc stability while promoting smooth short-circuit metal transfer. A mix of about 75% argon and 25% CO2 delivers that balance: argon stabilizes the arc and helps good bead formation, while CO2 adds a bit of reactivity that supports reliable short-circuit transfer and penetration control. Pure argon would be too inert for this mode, and pure CO2 tends to cause more spatter and less control on carbon steels. The other options either lack the right arc stability or introduce conditions (like more spatter or different bead characteristics) that aren’t ideal for short-circuit transfer on these steels.