In the AWS code ER70S-2 for mild steel, what does the 'S' denote?

• A. Semi-automatic
• B. Solid
• C. Uncoated solid electrode wire
• D. Shielding gas

Answer: (C)

The S in this AWS designation points to the form of the electrode. It shows you’re dealing with a solid wire rather than a flux‑cored or hollow electrode. That means there’s no flux inside the wire to generate shielding; the weld is protected by the shielding gas you use with the process. In practice, solid wires are copper‑coated for feeding and electrical contact, but the S designation itself is about the core being solid (unfluxed), not about any outer coating. This is why the option describing an uncoated solid electrode wire best matches what the S communicates.