Assessment of the role of micro defect nucleation in probabilistic modeling of cleavage fracture

The present study is concerned with the local conditions for initiation of cleavage in ferritic steels. A variety of SE(B), C(T) and CC(T) specimens has been tested. In a fractographic analysis, the cleavage triggering sites were determined. In a finite element analysis, the local mechanical field quantities at the instant of fracture were determined. The results reveal that beside the stress criterion, the nucleation of micro defects due to increasing plastic deformation for ms a second necessary condition for cleavage failure.