PHYSICAL FUNDAMENTALS OF LOCAL APPROACH TO ANALYSIS OF CLEAVAGE FRACTURE

摘要

Physical interpretation of regularities of metal fracture ahead of notch and sharp crack is supplied based on results of statistical modelling of microcrack nucleation and propagation in polycrystal. It is shown that not only local stress but also local plastic strain influences significantly fracture probability ahead of notch. This is due to both the influences of dislocation microstresses on the crack nucleus unstable equilibrium and the crack nucleus density dependence on the plastic strain value. It is demonstrated that plastic strain influences also sensitivity of local fracture stress of iron to the process zone volume. Main factors affecting the process zone size are ascertained. The findings on influence of grain sizes and plastic strain on Weibull parameters are discussed.