Study on cleavage fracture probability-load curves of ferritic steel 20MnMoNi55 by using the new local approach model

In this paper, the new local approach model (NLAM) is first adopted to predict the cleavage fracture probability-load curves of notched round bar tensile specimens of ferritic steel 20MnMoNi55 at the temperatures of 123 K and 223 K. Then, based on the obtained curve, the probability density function, and the extreme value theorem of function, two significant cleavage fracture probabilities are proposed. Finally, the proposed probabilities are employed to predict the load which is most likely to cause cleavage fracture of 20MnMoNi55 steel. The results show that when the value of cleavage fracture probability is 45.29%, the corresponding predicted load is basically equal to the average fracture load of the specimens. Besides, the load corresponding to the cleavage fracture probability of 59.7% is the most likely one to induce cleavage fracture of the structure.