Characteristics of copper shaped-charge liner materials at tensile strain rates of 10(sup 4) s(sup (minus)1).

摘要

We have studied the mechanical behavior of 81-mm shaped-charge liners made from oxygen-free electronic (OFE) and electrolytic tough pitch (ETP) copper at tensile strain rates of 10(sup 4) s(sup (minus)1) by using electromagnetic ring expansion. The OFE copper was processed to yield an uniform grain size of approximately 25 (mu)m, whereas the ETP material was reportedly processed in such a way as to encourage excessive grain growth and a broad distribution of grain sizes. However, the microstructures of the materials we studied are all similar, and we find no evidence of gross secondary grain growth in the ETP liners, although they do contain oxide inclusions. The OFE liners are characterized by reproducible stress-strain relationships nearly identical to independently processed OFE copper of comparable grain size. The flow stress of the ETP specimens, in contrast, is both lower and generally more erratic than that of the OFE specimens. Elongation at failure for the OFE linear materials are consistently large (0.55 (plus minus) 0.01) and are significantly larger than values observed for annealed 10-(mu)m OFE (0.49 (plus minus) 0.04). The ETP materials appear to show somewhat less elongation at failure, although their erratic behavior makes comparisons difficult. We suggest that the erratic behavior of ETP shaped-charge liners under test and their poor performance relative to OFE copper are the result of chemical impurities and related microstructural nonuniformities, rather than differences in grain size alone. 12 refs., 9 figs., 2 tabs.