Which of the following is a common material used as filler metal in welding?

The correct choice, ER70S-6, is a widely recognized filler metal used in gas metal arc welding (GMAW) and shielded metal arc welding (SMAW). This filler metal is made of a low carbon steel and is popular due to its excellent welding characteristics, including a good balance of strength, ductility, and good arc stability. It is specifically designed for welding mild and low alloy steels, and it can help produce high-quality welds with minimal defects.

This filler metal also has deoxidizers such as silicon and manganese, which help prevent porosity during the welding process, making it ideal for various applications, especially in structural and fabrication work. The designation "ER70S-6" indicates that it is a filler rod, the number "70" signifies the minimum tensile strength of 70,000 psi, and the "-6" denotes that it has a specific composition suitable for a range of welding uses.

On the other hand, while Aluminum 6061, Stainless Steel 304, and Copper 101 are materials commonly used in various applications, they are not typically referred to as filler metals for welding processes like ER70S-6. Instead, they might be the base materials that require different types