Brittleness

Article By:

Lewandowski, John J. Department of Materials Science and Engineering, Case Western Reserve University, Cleveland, Ohio.

Last reviewed:October 2019

DOI:https://doi.org/10.1036/1097-8542.095900

The catastrophic fracture of a material or structure without a significant amount of prior extension or plastic deformation. The energy absorbed during fracture is highly dependent on whether a material or structure behaves in a brittle or ductile manner. Materials or structures that fracture in a brittle manner exhibit small amounts of plastic deformation and extension. This requires a much lower amount of energy in the fracture process compared to a material or structure that fails in a ductile manner. Figure 1 shows the effect of a change in test temperature on the energy absorbed during the fracture of some materials, where the energy absorbed during fracture at low temperatures is significantly less than that absorbed at higher temperatures. Materials or structures in the low-temperature regime are failing via brittle fracture. Increasing the test temperature produces a significant increase in the fracture energy, where the materials behave in a much tougher manner and exhibit a more ductile fracture appearance. At intermediate temperatures, a brittle-to-ductile transition is shown. Brittleness and brittle fracture are exhibited by a number of materials, including glass, minerals, some polymers, cast iron, concrete, some refractory metals, most ceramic materials, and a number of different steels tested below their brittle-to-ductile transition temperature.

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