Damage Mechanisms Affecting Fixed Equipment in the Refining Industry

Brittle fracture

Brittle fracture

is a type of catastrophic failure in materials, characterized by rapid crack propagation with little or no plastic deformation. This fracture occurs without significant prior deformation and often under relatively low-stress conditions compared to ductile fracture. Key features and considerations of brittle fracture include:

Fracture Mechanism

Brittle fracture typically propagates by cleavage, where atomic bonds are broken along specific crystallographic planes. This process requires less energy than ductile fracture, which involves plastic deformation.


The fracture surface of brittle materials usually appears flat and shiny, often with a granular texture. Features like river patterns, chevrons, and fracture markings can indicate the fracture origin and direction of crack propagation

Material Types

Brittle fracture is common in materials with low toughness, such as ceramics, glass, and some high-strength metals and alloys (especially at low temperatures

Temperature Sensitivity

Many materials exhibit a transition from ductile to brittle behavior as the temperature decreases. The temperature at which this transition occurs is called the ductile-to-brittle transition temperature (DBTT).

Stress Concentrations

Brittle fracture is more likely to initiate at stress concentrators like notches, sharp corners, or pre-existing cracks. These features create localized areas of high stress that can exceed the material’s fracture toughness.

Loading Rate

High strain rates can also promote brittle fracture. Rapid loading reduces the time available for plastic deformation, leading to a more brittle response

Fracture Toughness

This is a material property that describes its ability to resist fracture in the presence of a flaw. Materials with low fracture toughness are more susceptible to brittle fracture

Examples and Prevention

Historical examples include the catastrophic failure of Liberty ships during World War II, which experienced brittle fracture due to low temperatures and poor material quality. Preventive measures include using materials with higher fracture toughness, avoiding sharp corners in design, controlling loading rates, and operating above the DBTT when possible

Understanding and mitigating brittle fracture involves careful material selection, design considerations to minimize stress concentrations, and controlling environmental factors like temperature.


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