In this investigation,by means of a statistics of a large number of fracture me-chanics and surface
parameters of fracture
mechanics and surface
parameters of Notchedspecimens,it was found that the occuring probability of the fracture at the left side of themaximum stress location ahead of a notch root is larger than that at the right side and the oc-curing probability at the left side increases with decreasing temperatures.The initiation ofcleavage can only occur at a small distance from a notch root.With the increase of the dis-tance from a notch root,the fracture probability increases and at some distance it reachs amaximum value.By analyzing the facts described above,it was suggested that two condi-tions must be satistied for the cleavage fracturing in notched specimens,that is,the plasticstrain ε_p ahead of a notch root must be larger than a critical value ε_(pc) for initiating a microc-rack and the principal stress σ_(yy) must be larger than the local cleavage fracture stress σ_f for thepropagation of the microcrack. The cleavage fracture in notched specimens also has a situa-tion of initiation controlled. Based on a new cleavage
fracture model,the statistical results ofthe location of initiating cleavage and the influence of the fractuse mechanics parameters onthe fracture behavior were analysed.