Mechanisms of high-strain-rate deformation and fracture of fine-grained unalloyed uranium upon explosive loading

The study of the microstructure and properties of quasi-statically extruded fine-grained uranium before and after explosive loading has shown that the main mechanism of its high-strain-rate deformation is multiple twinning. The nucleation of spall and shear microdamages upon explosive loading occurs at oxycarbonitride inclusions, just as in the coarse-grained cast metal upon the analogous regime of explosive loading. The absence of an increase in the spall strength of uranium upon a decrease in the initial grain size by a factor of 100–250 is related to the presence of a significant amount of impurities (to 1.5 ± 0.2 vol %) in the material.