AWS Certified Welding Inspector — FundamentalsWelding MetallurgyEasy
A welding inspector observes a weld discontinuity characterized by a narrow, sharp crack located within the weld metal, typically running longitudinally or transversely. This crack appeared immediately after welding. What type of cracking is most likely indicated by this description?
- ALamellar tearing
- BReheat cracking
- CHydrogen-induced cracking (HIC)
- DSolidification cracking (Hot cracking)
Show answer & explanationAnswer & explanation
Correct answer: D. Solidification cracking (Hot cracking)
Solidification cracking, also known as hot cracking, occurs during the final stages of weld metal solidification. It is characterized by narrow, sharp cracks that form in the weld metal, often along the centerline, due to the inability of the partially solidified metal to withstand shrinkage stresses. This type of cracking typically appears immediately after welding.
Why the other options are wrong
- A. Lamellar tearing occurs in the base metal, parallel to the rolling direction, and is associated with through-thickness stresses.
- B. Reheat cracking occurs in the HAZ of certain alloy steels during post-weld heat treatment or high-temperature service.
- C. Hydrogen-induced cracking (cold cracking) occurs after the weld has cooled, sometimes hours or days later, and is typically intergranular.
Solidification Cracking (Hot Cracking)
A type of cracking that occurs in the weld metal during the final stages of solidification, characterized by narrow, sharp cracks that appear immediately after welding.
- Occurs in the weld metal.
- Happens during solidification (hot condition).
- Appearance: narrow, sharp, often longitudinal or transverse.
- Caused by shrinkage stresses on low-ductility liquid films at grain boundaries.
Memory trick: Hot crack's swift appearance in the weld means it couldn't solidify right.