Which term describes the distance from the original surface to the deepest point of fusion?

• A. Bead height
• B. Penetration depth
• C. Root reinforcement
• D. Root penetration

Answer: (D)

Root penetration is the distance from the original surface to the deepest point of fusion along the weld root. This term specifically describes how far the molten metal has fused into the base metal at the root of the joint, which is the deepest point of fusion. It’s the precise measure used to evaluate how well the root of the weld has fused.

Bead height is about how tall the weld bead sits above the surface, not how deep the fusion goes. Root reinforcement refers to extra material built up at the root, not the depth of fusion. Penetration depth is a general term for depth of fusion but doesn’t specify the root location; root penetration names the depth at the root, matching what the question describes.