Keyword: «fracture toughness»

It is assumed that the decrease in crack resistance at low temperature may be associated with a decrease in the size of the plastic zone. A large plastic zone has the effect of «blunting» the crack tip. With a decrease in temperature, due to an increase in the yield strength and a decrease in the size of the plastic zone, this effect is significantly reduced, which leads to a significant decrease in crack resistance. Using a combination of classical mechanics and fracture mechanics approaches, an associated expression for a crack resistance is obtained. The expression qualitatively describes the experimentally obtained curves of the ductile-brittle transition zone. It is shown that, in addition to such factors as the scale effect, features of the crystal structure of the metal, the parameters of classical mechanics and fracture mechanics can make a significant contribution to the phenomenon of cold brittleness.