What does the term 'brittle fracture' refer to in pressure piping?

The term 'brittle fracture' specifically refers to a failure mode characterized by the sudden breaking of a material when it is subjected to stress, without going through a plastic deformation phase. This means that the material does not show any noticeable deformation before it fails; instead, it fractures abruptly. In the context of pressure piping, this can occur under certain conditions, such as low temperatures or during high-stress scenarios, where the material’s toughness is insufficient to absorb the energy applied to it.

One key aspect of brittle fracture is that it can lead to catastrophic failures in piping systems. Understanding this concept is crucial for those in the field because materials used in pressure piping must be chosen and maintained carefully to prevent such sudden failures.

The other options describe different phenomena that do not align with the definition of brittle fracture. Gradual wear relates to fatigue failures, which occur over time with repeated stress but are not categorized as brittle fractures. The notion that brittle fractures only occur at low temperatures limits the understanding of the issue since this type of failure can happen at various temperatures depending on the material properties. Lastly, a failure that involves melting does not fall under the concept of brittle failure, which is purely about the fracture mechanism rather than thermal degradation.