RESIDUAL MICROSTRUCTURE OF A SHAPED-CHARGE JET FRAGMENT

A recovered copper shaped-charge jet fragment has been built up by copper electrodeposition for the first time to allow it to be systematically sectioned and polished for detailed observations by optical and electron microscopy. The residual jet fragment microstructure was observed to have a recrystallized grain structure and dislocation substructures similar to those in the undeformed copper shaped charge liner cone. However, the average grain size in the recrystallized jet fragment was 15 mum compared to 45 mum for the liner. More significantly, however, SEM examination near the tips (or ends) of the jet fragment exhibited voids and coalesced void tunnels elongated axially within the fragment geometry, which are believed to have resulted during jet elongation and breakup by diffusion and viscous growth at high strain and strain rate. The observation of additional porosity in the interior of the jet fragment is supported by the lack of any similar observations in the surrounding and supporting (built up) copper electrodeposit.