The role of dynamic recrystallization in [001] single-crystal W and W-Ta alloy ballistic rod penetration into steel targets

Abstract

The microstructures of long rod [001] single-crystal penetrators of W grown by CVD and zone melt processing, and W-5% Ta grown by zone melt (ZM) processing, were examined before and after penetration into RHA steel targets, by optical metallography and transmission electron microscopy. The initial Vickers microhardness values for the CVD-W rods was 417 VHN in contrast to 485 VHN for the ZM-W and W-5% Ta rods as a consequence of an order of magnitude larger dislocation density. Both the CVD-W and ZM-W exhibited less dense head flow associated with adiabatic shear bands and dynamic recrystallization (DRX) than the ZM-W-5% Ta, but all penetrators exhibited erosion tube formation in the penetration channel. These tube and erosion debris particles exhibited dense, overlapping shear bands composed of DRX grains or areas with larger, equiaxed grains resulting from residual grain growth. These observations suggest that controlling the penetrator head flow by solute-induced DRX may control penetration.