What indicates a hot tear in castings?

A hot tear in castings is characterized by a ragged line of variable width with branches. This type of defect typically occurs during the cooling phase when the metal is still in a relatively plastic state. The molten metal contracts as it solidifies, and if there are internal stresses or uneven cooling, it can lead to fractures.

The ragged appearance comes from the nature of the crack where the solidifying metal tears apart rather than cleanly separating, resulting in jagged edges. The branching indicates that the tear has multiple paths, which is common in situations where the metal is under stress, further reflecting the irregular nature of the defect. This characteristic differentiates hot tears from other types of discontinuities which usually present with more uniform or less intricate patterns.

Understanding this helps in identifying and addressing defects in casting processes, ensuring the integrity and reliability of the final products. Furthermore, recognizing the distinct visual patterns of hot tears can assist in implementing corrective measures during manufacture.