The electrode code ER70S-2 indicates the electrode wire is for which material?

• A. Mild steel electrode wire
• B. Stainless steel electrode wire
• C. Aluminum electrode wire
• D. Copper electrode wire

Answer: (A)

In AWS electrode/wire classifications, ER70S-2 identifies a carbon steel (mild steel) solid welding wire. The “70” points to a weld-metal tensile strength around 70 ksi, and the “S” means it’s a solid wire (not flux-cored). The “-2” portion indicates a specific deoxidizer package (manganese and silicon) that makes it forgiving to slightly dirty or rusty carbon steel surfaces. This combination makes it a common, general-purpose filler for welding mild steel.

The other materials listed—stainless steel, aluminum, and copper—use different filler metals with classifications tailored to those metals. So the ER70S-2 designation specifically signals a mild steel wire, not stainless, aluminum, or copper.