What is the role of filler metal in arc spot welding during a deck qualification?

• A. It fills the weld and contributes to joint strength
• B. It is optional
• C. It is only used for decorative purposes
• D. It must be avoided

Answer: (A)

In arc spot welding, the filler metal's role is to fill the joint and contribute to the joint’s strength. Adding filler metal builds up the weld bead, restoring the cross‑section that must be carried by the weld and providing the alloying elements needed to meet the required mechanical properties. In a deck qualification, you’re aiming for a weld that has the specified throat, fusion, and strength, and the filler metal helps achieve that by ensuring proper weld volume, fusion with the base metal, and resistance to service loads. Without filler, you risk underfill and inadequate strength, which is not acceptable for structural deck welds. The filler is not decorative or optional; it’s essential to meet the design and code requirements.