MICROMECHANISMS OF DYNAMIC FRACTURE OF DUCTILE HIGH-STRENGTH STEEL

Multiscale micromechanisms of dynamic fracture of ductile high-strengt h Cr-Ni-Mo-V steel are studied by combining a laser interference techn ique and conventional techniques of optical and electron microscopy. T wo scale levels of high-rate strain and fracture were found to form th e translational and rotational modes of material motion during shock w ave propagation-mesoscopical (0.1-10 mum) and superstructural (50-500 mum). The kinetic and mechanical characteristics of materials at the a djacent scale levels turn out to be in opposite phases relative to eac h other, strength-characteristics closely connecting with the particle velocity dispersion. Heterogeneous dynamic deformation appears to be realized either in the form of shear bands or in the form of rotationa l vortices depending on the ratio of particle velocity dispersion and average particle velocity. During dynamic deformation the changing of carbide sizes and lattice parameter occurs, the intensity of these pro cesses being dependent on the mesovolume velocity dispersion as well.