Criterion of fracture toughness in low carbon steel under uniaxial tension

Criterion of fracture toughness in low carbon steel under uniaxial tension which is fulfilled when coefficient of toughness of the material, strained in the neck becomes equal to hardness of strained condition, is established; it permits to predict the parameters of fracture toghness by the microcleavage model if the fundamental characteristics of the material (resistance to the microcleavage Rsub(mc) and flow stress σsub(te)) and power conditions of loading of the sample under tension are known. Complete diagram of the ductile fracture in the carbon steels (St 10 St20) is presented; possibility of its practical use is shown