Thermal shock is defined as fracture due to rapid temperature change.

• A. Fracture due to slow heating
• B. Fracture due to chemical reaction
• C. Fracture due to repeated loading
• D. The fracture of the material as a result of a rapid temperature change

Answer: (D)

Thermal shock occurs when a material fractures because of a rapid change in temperature that creates internal stresses. When one region heats or cools much faster than another, it wants to expand or contract differently, generating tensile and/or compressive stresses inside the material. If these thermal stresses exceed the material’s strength, cracks form or propagate. A slow temperature change doesn’t produce the same steep temperature gradients, so thermal-shock cracking is unlikely. Chemical reactions describe another failure mechanism, not thermal shock, and repeated loading leads to fatigue rather than fracture from a temperature change. So, describing fracture as a result of a rapid temperature change exactly matches the mechanism behind thermal shock.