What is the recommended gas flow rate range for MIG welding on mild steel with 75/25 gas?

• A. About 60 to 70 CFH.
• B. About 20 to 25 CFH.
• C. About 5 to 10 CFH.
• D. About 100 to 120 CFH.

Answer: (B)

Gas flow rate in MIG welding must create a stable shielding envelope around the weld pool. For mild steel using a 75/25 (argon-CO2) shielding gas, the typical range kept by most setups is about 20 to 25 CFH. This level provides enough gas to protect the molten weld from the atmosphere without generating excessive turbulence or wasting gas.

If the flow is too low, shielding won’t fully cover the weld, increasing the risk of porosity and contamination. If it’s too high, the gas can blow around the joint, cause turbulence, push away the shielding, and waste gas. Among common options, 20–25 CFH sits in the optimal range, while the others are either too high or too low for reliable shielding.