Local Criterion for Cleavage Fracture : Structural and Mechanical Approach

Abstract
On the base of physical-and-mechanical modelling for cleavage microcrack behaviour a new local criterion for cleavage fracture is formulated. Cleavage fracture of pressure vessel steel under various loading history is investigated. It has been experimentally shown that for steels after static prestrain by tension and cyclic prestrain brittle fracture critical stress is described by increasing function of Odqvist's parameter, in the same time plastic precompression results in the significant embrittlement of steel and transition from transcrystalline cleavage fracture to intercrystalline one. Proposed criterion application for predicting fracture toughness dependence on temperature K_IC(T) and prestrain influence on K_IC is shown