What defect is indicated by a rough, crater-like opening at the end of a bead?

• A. Porosity.
• B. Crater crack or crater defect.
• C. Undercut.
• D. Lack of fusion.

Answer: (B)

Crater cracks form at the end of a weld bead when the weld pool solidifies and cooling/ shrinkage create a crack at the crater edge. Stopping the weld abruptly or leaving the crater poorly filled can leave tensile stresses that crack as the bead ends, showing up as a rough, crater-like opening at the end. This specific appearance points to a crater defect. Porosity would show as gas pockets within the weld metal, not a crater at the end. Undercut appears as a groove along the weld toe, and lack of fusion shows incomplete bonding between weld metal and base metal.