cold-short

from The Century Dictionary.

• Brittle when cold: as, cold-short iron.
• noun In founding, a seam in a casting caused by the congealing of the metal so rapidly as to prevent a proper filling of the mold. Also cold-shut.

from the GNU version of the Collaborative International Dictionary of English.

• adjective (Metal.) Brittle when cold (that is, below a red heat).

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective brittle when cold