AN INVESTIGATION OF QUASI-CLEAVAGE FRACTURE IN STEEL

The quasi-cleavage fracture has been studied in conjunction with the stressstrain behaviour of steel specimens. Consideration of the results obtained on dif-ferent varieties of steel indicate that the quasi-cleavage fracture may be interpretedin terms of certain transition fracture mechanism as follows: Microcleavage cracks are nucleated at certain places of high tensile strss con-centration, subsequently each of them propagates along the cleavage plane in grainsalready deformed and finally they merge together by microplastic coalescence.According to the above conception, the interaction between the cleavage crack andthe plastic deformation may be regarded as the most important characteristics ofquasi-cleavage fractures. Using quantitative fractography, correlation between thefractographic features of specimens and the parameters of its certain mechanicalproperties may be established.