Shrinkage cavity is:

• A. A common irregular void found in all metals.
• B. A void left in cast metals as a result of solidification shrinkage and the progressive freezing of metal toward the center.
• C. The internal voids in a material.
• D. The measure of the acidity of a solution.

Answer: (B)

Shrinkage cavities occur when metal contracts as it changes from liquid to solid. In a casting, the outer portions freeze first and form a solid shell, while the interior remains molten. As solidification proceeds toward the center, the metal volume decreases. If enough liquid metal can’t feed this shrinking region through the gates and risers, a void is left behind—the shrinkage cavity. This is a defect specifically tied to solidification in castings, unlike general internal voids or measurements of acidity in a solution.