DYNAMIC FRACTURE PHENOMENA IN HIGH-STRENGTH STEELS

Brittle metals subjected to blast loads shatter into a large number of very small particles, the number and size of which are well characterized by the semiempirical cumulative distribution function of Mott. This function, however, contains no information regarding either the manner of breakup or the reason for a particular distribution. An earlier analytical study of the phenomenology of brittle fragmentation used statistical arguments to establish relationships between the energies associated with crack branching and the Mott parameters that characterize the particle distribution. That model predicts that the average mass of a particle from the shattered body is proportional to the fourth power of the crack-branching stress-intensity factor. In the present work on hypereutectoid steels, the ratio (KH/KIC)3.4 was experimentally determined to be linearly related to the average particle mass in reasonably good agreement with the model prediction, where KH is the dynamic stress intensity factor for incipient microbranching (hackle), and KIC is the plane-strain fracture toughness.