Application of a new cleavage fracture criterion for fracture toughness prediction for RPV steels

ABSTRACT In the present paper, approaches for prediction of cleavage fracture proposed by authors over recent years are briefly reviewed. A new local criterion of cleavage fracture and its application are considered. Local criterion of cleavage fracture formulated in a probabilistic manner consists of cleavage microcrack nucleation condition and condition for their start and propagation through various barriers such as microstresses, grain and dislocation substructure boundaries. As distinct from universally accepted criterion in which microcrack nucleation occurs on the plastic deformation beginning (σeq=σY), cleavage microcrack nucleation according to the formulated condition depends on the maximum principal stress, plastic strain and temperature. On the basis of the proposed criterion, a probabilistic model for fracture toughness prediction (known now as Prometey model) was developed and verified by application to reactor pressure vessels (RPV) materials in the initial, moderately irradiated and highly embrittled states. The Prometey model and other applications of the proposed criterion are briefly considered. The predicted results are compared with test results and the Master Curve.