In ER70S-6, what feature helps reduce porosity in welding plain carbon steel?

• A. Higher carbon content.
• B. Deoxidizers.
• C. Lower melting point.
• D. Increased shielding gas.

Answer: (B)

Porosity in a weld comes from gases trapped in the molten metal as it solidifies. In ER70S-6, the filler wire includes deoxidizers—mainly silicon and manganese—that react with oxygen (and sulfur) in the molten pool. These deoxidizers form stable oxides that bind those elements and help remove them from the liquid metal, reducing the chance that gas pockets will form as the weld cools. This keeps the weld metal cleaner and less prone to porosity, even when surfaces aren’t perfectly clean or when a common shielding gas is used.

Higher carbon content would raise strength or cracking risk rather than directly address porosity. A lower melting point isn’t a defining feature used to control porosity in practice. Increasing shielding gas can reduce porosity by protecting the weld from air, but that’s an external factor, whereas ER70S-6 is designed with its own deoxidizers to minimize porosity from within the filler metal itself.