Which shielding gas specification is used with ER70S-2 electrode wire?

• A. 100% CO2
• B. 75%-95% Argon/Balance CO2
• C. Argon
• D. Helium/CO2

Answer: (B)

ER70S-2 is a common MIG welding wire for mild steel that performs best with an argon-rich shielding gas rather than pure CO2 or inert gas alone. Using a mixture of mostly Argon with a smaller amount of CO2 provides a stable arc and good bead appearance while still giving enough penetration for typical joint joints. The range of 75% to 95% Argon with the balance CO2 is a common, well-balanced choice for this wire, helping control spatter and glow while maintaining nice fusion.

Pure CO2 can increase spatter and create a harsher bead, and Argon alone doesn’t provide the active balance that improves transfer for this wire. Helium/CO2 is used for different, higher-heat applications and isn’t the standard choice for ER70S-2.