RESIDUAL MICROSTRUCTURE OF A SHAPED-CHARGE JET FRAGMENT

A recovered copper shaped-charge jet fragment has been built up by cop per electrodeposition for the first time to allow it to be systematica lly sectioned and polished for detailed observations by optical and el ectron microscopy. The residual jet fragment microstructure was observ ed to have a recrystallized grain structure and dislocation substructu res similar to those in the undeformed copper shaped charge liner cone . However, the average grain size in the recrystallized jet fragment w as 15 mum compared to 45 mum for the liner. More significantly, howeve r, SEM examination near the tips (or ends) of the jet fragment exhibit ed voids and coalesced void tunnels elongated axially within the fragm ent geometry, which are believed to have resulted during jet elongatio n and breakup by diffusion and viscous growth at high strain and strai n rate. The observation of additional porosity in the interior of the jet fragment is supported by the lack of any similar observations in t he surrounding and supporting (built up) copper electrodeposit.