LOCAL CRITERION FOR CLEAVAGE FRACTURE - STRUCTURAL AND MECHANICAL APPROACH

On the base of physical-and-mechanical modelling for cleavage microcra ck behaviour a new local criterion for cleavage fracture is formulated . Cleavage fracture of pressure vessel steel under various loading his tory is investigated. It has been experimentally shown that for steels after static prestrain by tension and cyclic prestrain brittle fractu re critical stress is described by increasing function of Odqvist's pa rameter, in the same time plastic precompression results in the signif icant embrittlement of steel and transition from transcrystalline clea vage fracture to intercrystalline one. Proposed criterion application for predicting fracture toughness dependence on temperature K-IC(T) an d prestrain influence on K-IC is shown.