Fracture toughness

A material's fracture Toughness is its Resistance to the onset of crack growth. It is a fracture Mechanics term and is described using the material's critical stress intensity factor - the point at which forced fracture occurs.

The Fracture toughness depends on the material. In identical materials, it decreases as the 0.2 percent yield point increases. However, as in the case of notched-bar impact Work, for example, the fracture toughness increases as the temperature increases.

Fracture toughness is determined using compact tensile tests. This involves using Vibration stress to initiate a crack in a tensile test piece with a central, angular notch. After the sample cracks, the crack propagation is measured and the stress at which the crack became unstable is read off.

While Ceramics exhibit poor fracture toughness, most Metals benefit from good fracture toughness.