Which two electrodes are most commonly used for welding?

The correct answer highlights ER70 S-3 and ER70 S-6 as the most commonly used electrodes for welding, particularly when working with carbon steel. These electrodes are part of the ER70 series, which indicates their suitability for welding carbon steel applications, providing a good balance of strength and ductility.

ER70 S-3 is known for its versatility and ability to produce strong welds in various positions, which is why it's frequently chosen for both automotive and general fabrication projects. Similarly, ER70 S-6 provides excellent performance in terms of tensile strength and impact resistance, making it ideal for applications where these properties are critical.

The popularity of these electrodes is due to their effectiveness in delivering quality welds on mild steel and their compliance with industry standards, including those outlined in the D1.1 code, which governs structural welding. This adaptability and reliability make them the go-to options for many welders in the field.

Other choices list electrodes that, while they may have specific applications, are not as widely utilized as ER70 S-3 and ER70 S-6 in general welding practices. Thus, the selection of the correct electrodes is vital in achieving structural integrity and meeting code requirements in welding projects.