ASPECTS OF DYNAMIC RECRYSTALLIZATION IN SHAPED CHARGE AND EXPLOSIVELYFORMED PROJECTILE DEVICES

Under a shock wave, a shaped charge (SC) liner or an explosively forme d projectile (EFP) device transforms into a jet and a slug. At various laboratories, it was found that the transformation was closely relate d to extensive plastic flow occurring at high strain rates. Along with the shape transformation, there is evidence of changes in hardness, s trength, grain configuration, microstructure, and resultant texture in the slug when compared to the starting liner. This article examines t he effect of material parameters on jet and slug formation. Based on m icrostructure (metallography and transmission electron microscopy) and texture data, an analysis is made of the recovery and recrystallizati on processes which are believed to be closely associated with the defo rmation. Grain rotations and shifts in texture are described from the starting liners to the recovered slugs. While fully recrystallized gra ins are found in a ''soft'' recovered copper EFP slug, only partial re crystallization is achieved in a tantalum counterpart. The difference in extent of recrystallization of copper and tantalum EFP slugs is ana lyzed. An attempt is made to explain the difference in terms of the de formation structures between the two types of metal. Experimental evid ence tends to support a grain rotation concept for recrystallization p henomena.