A simplified expression for low cleavage probability calculation

This article describes an analysis made to develop a simplified stress-based criterion for brittle fracture focussed on the lowest probability of failure. For that, on the basis of fine numerical interpretation of two series of fracture-tests on 16MND5 reactor vessel steel, a number of variables were proposed:
• A stress threshold σth below which cleavage cannot occur. This stress is determined by testing on notch tensile specimen at low temperature.
• A minimum toughness Kmin(T) required to make a crack unstable. The originality is here to consider this parameter depends on temperature.
• For KJ > Kmin(T), a volume susceptible to cleavage, defined as the volume of material subjected to stress exceeding the threshold stress and noted Vth, representative of the fracture probability.These three variables are explained in the article then used to establish a tentative criterion for expressing the risk of brittle fracture, in the presence or absence of a crack.