The propagation of a crack through the thickness of a material. It may be further described by nature of the surface at the break, e.g. brittle fracture.
- Brittle fracture – A break in a brittle piece of metal which failed because stress has exceeded cohesion. Brittle materials crack without significant deformations of the crack surfaces that retain a shiny and smooth appearance.
- Ductile fracture – A crack in a material that behaves in a ductile manner. This is characterized by significant deformations of the fractured surface.