Magnetic Particle Inspection Level 1 Practice Exam

Which of the following best describes "hot tears"?

1. Defects occurring during cooling of metal

2. Cracks formed during welding

3. Failures due to thermal shock

4. Corrosion-related discontinuities

The correct answer is: Defects occurring during cooling of metal

"Hot tears" refers to defects that occur during the cooling process of metal as it transitions from a liquid to a solid state. This phenomenon happens when the metal is not fully solidified and experiences stresses that exceed its integrity. These stresses can be caused by thermal contraction, which occurs as the metal cools down and solidifies. The critical aspect here is that these tears develop while the metal is still hot, typically in the temperature range where it is partially molten. Hot tears are particularly significant in casting processes. If the cooling rate is uneven or the material shrinks excessively during cooling, it can lead to the creation of these defects. Recognizing this allows for better control of the cooling process and the design of metal components to mitigate the risk of such defects occurring. Understanding hot tears is crucial for ensuring the structural integrity and performance of metal parts in various applications.