Red Seal Welder Practice Exam 2026 - Free Red Seal Welder Practice Questions and Study Guide

The correct answer is ER70S-6, a common type of filler metal used in MIG welding, particularly for welding carbon and low-alloy steels. This filler metal has a high tensile strength and is known for its excellent weldability and impact toughness. It contains a balanced composition of iron and a small percentage of alloying elements like manganese and silicon, which contribute to its ability to produce strong, ductile welds.

ER70S-6 also features a high deoxidant content, which makes it effective for welding clean materials and those that may have surface contaminants. This is crucial in MIG welding, where ensuring a good weld quality is reliant on proper clean surfaces. Because of these properties, ER70S-6 is preferred in many applications, including structural fabrication, automotive repair, and general manufacturing where strong welds are required.

The other filler metals listed, while also suitable for specific applications, are not as commonly used for MIG welding on carbon steels. For example, ER308L is typically used for welding stainless steels, ER4047 is used primarily for aluminum alloys, and ER5356 fits aluminum applications as well, but not generally for carbon steel, which is the primary focus in many MIG welding scenarios.