A comparison of shaped charge liner cone and recovered jet fragment microstructures to elucidate dynamic recrystallization phenomena

Abstract

In several previous publications, we have argued that reductions in the starting grain size of copper [l] and tantalum [2] shaped charge liner cones by as much as a factor of 102 in recovered slug and jet fragments following detonation provided unambiguous evidence for dynamic recrystallization (DRX) as proposed earlier by Meyers, et al 13, 41. This evidence was based upon the fact that such a dramatic grain refinement (from roughly 35 pm to 0.3 pm) could only be explained by DRX especially in cases where the grain boundary misorientations averaged >15O. Furthermore, Chokshi and Meyers [4] argued that treatments of DRX by Sandstrom and Lagneborg [5] and Derby and Ashby [6] had developed similar expressions for a steady-state grain size proportional to the reciprocal square root of the strain rate. They utilized this proportionality along with other related assumptions to arrive at steady-state grain sizes between 0.1 and 0.01 pm for copper having undergone DRX at strain rates above 104 s-1.