ER70S-3 (GMAW) description: A general purpose welding wire for fabrication of mild steel. Contains silicon and manganese as deoxidizers. Usually used with 75/25 (argon/CO2) shielding gas or with higher contents of argon, such as 90/10. Can also be used with 100% CO2. Qualified to AWS A5.18 ER70S-3.