Why is ER70S-6 commonly chosen for welding plain carbon steel in GMAW?

• A. It produces decorative weld finishes.
• B. It provides good all-around weld quality, deoxidizers to reduce porosity, and works well with common shielding gases.
• C. It requires no shielding gas.
• D. It has the lowest cost but weak mechanical properties.

Answer: (B)

In GMAW of plain carbon steel, porosity is often caused by oxide films and contaminants in the weld pool. ER70S-6 is formulated with silicon and manganese deoxidizers that actively scavenge oxygen and bind oxides as the weld metal solidifies. This reduces porosity and improves weld integrity, giving good all-around weld quality for typical carbon steels. It also pairs well with common shielding gas mixtures used in MIG welding, making it versatile for standard shop setups. That combination—effective deoxidizers to control porosity, solid weld quality, and compatibility with typical shielding gases—explains why it’s commonly chosen.