Which statement about crater cracks is correct?

Which statement about crater cracks is correct?

• A. Crater cracks are star-shaped cracks that extend from the crater of a weld to the edge of the weld.
• B. Crater cracks occur in all welds without exception
• C. Crater cracks are always easy to detect
• D. Crater cracks are the same as porosity

Answer: (A)

Crater cracks show up as star-shaped cracks that originate at the end of the weld bead, the crater, and extend toward the weld edge. This happens because the last portion of the weld cools and contracts under restraint, creating tensile stresses that pull the solidifying metal and produce cracks radiating from the crater. Hydrogen in the weld metal can aggravate this cracking tendency, but the defining feature is the star-like pattern from the crater outward, which is why this description fits crater cracks best. It's not true that every weld will have crater cracking; it depends on factors like material, hydrogen content, heat input, and residual stresses. They aren’t always easy to detect—some cracks are hidden inside the weld or near the surface and require appropriate testing to reveal. And crater cracks are a different defect from porosity, which are gas pockets trapped in the weld metal rather than cracks extending from the crater.

Crater cracks show up as star-shaped cracks that originate at the end of the weld bead, the crater, and extend toward the weld edge. This happens because the last portion of the weld cools and contracts under restraint, creating tensile stresses that pull the solidifying metal and produce cracks radiating from the crater. Hydrogen in the weld metal can aggravate this cracking tendency, but the defining feature is the star-like pattern from the crater outward, which is why this description fits crater cracks best.

It's not true that every weld will have crater cracking; it depends on factors like material, hydrogen content, heat input, and residual stresses. They aren’t always easy to detect—some cracks are hidden inside the weld or near the surface and require appropriate testing to reveal. And crater cracks are a different defect from porosity, which are gas pockets trapped in the weld metal rather than cracks extending from the crater.