NOVEL DEFORMATION PROCESSES AND MICROSTRUCTURES INVOLVING BALLISTIC PENETRATOR FORMATION AND HYPERVELOCITY IMPACT AND PENETRATION PHENOMENA

Light metallography and transmission electron microscopy techniques af fording unique observations of microstructural issues in connection wi th a related set of novel, high-strain-rate deformation processes prov ide some fundamental insight into the following areas: shock-wave-indu ced twinning, explosive welding, shaped charge development, explosivel y-formed penetrator phenomena, hypervelocity impact cratering in metal targets, and long, dense rod penetration/perforation of thick metal t argets. Although shock wave phenomena are precursors in all these proc esses, deformation twins are rarely observed in the residual, process microstructures. In the case of hypervelocity impact craters, no defor mation twins are observed in the crater-related target microstructures . Microbands that appear to be related to twins are observed. Melt-rel ated phenomena are observed only in the explosive weld-wave interfaces . Jetting phenomena related to shaped charges and crater rim formation are dominated by dynamic recrystallization, which provides a mechanis m for extreme plastic flow in the solid state. Differences observed be tween rod penetration of rolled homogeneous armor and Ti-alloy thick t argets manifest themselves in distinct microstructural differences tha t also do not include melt phenomena. (C) Elsevier Science Inc., 1996.