Which filler metal is commonly used in gas metal arc welding (GMAW)?

• A. ER70S-2
• B. ER70S-6
• C. ER120S-1
• D. ER308L

Answer: (B)

In gas metal arc welding (GMAW), the filler metal commonly designated as ER70S-6 is particularly favored due to its properties and composition. This filler metal is classified under the AWS classification system for welding wires and offers excellent weldability, making it suitable for a wide range of applications, including structural steel and similar materials.

ER70S-6 contains a higher level of manganese and silicone compared to ER70S-2, thereby enhancing its ability to provide a clean, smooth weld with good impact properties. It is especially effective for welding while minimizing porosity and defects, which is critical for maintaining the integrity of the welded joint.

The inclusion of the 'S' in the designation indicates that this wire is solid and specifically suited for shielded metal arc welding processes, while the '70' indicates a minimum tensile strength of 70,000 psi.

The other options, while they are filler metals used in various welding processes, are either less common for GMAW or used for specific applications or materials. Hence, ER70S-6 stands out as the most appropriate choice for this specific welding method.