The ability of materials, and especially metals, to be plastically formed and deformed by explosive, shock or impact phenomena is a truly remarkable feature which often seems to be misunderstood in the context of solid-state or solid-phase behaviour. Shaped charge jet and slug formation is characterised prominently by dynamic recrystallisation which may occur in deformation-recrystallization cycles, providing a mechanism for extreme plastic flow in jetting. There was no evidence for melting or melt-related phenomena. Hypervelocity impact crater development is also dominated by dynamic recrystallisation in a narrow flow zone where target material is jetted into the crater rim. The crater rim can particulate by velocity gradients along the jetting rim just like the shaped charge jet. Like the shaped charge, there was no significant melt phenomenon associated with the cratering process, and extreme plastic, high-strain-rate flow occurs in the solid state. Microbands are created in a zone removed from the crater wall in copper targets in response to hypervelocity impact which, like deformation twins, are coincident with the trace of primary (111) planes. Their density and extent increase with both impact velocity and grain size. Neither microbands nor deformation twins are observed in recovered shaped charge slug and jet fragments.
Comparison of jetting-related microstructures associated with hypervelocity impact crater formation in copper targets and copper shaped charges
Vergleich des mit der Bildung von Überschall-Einschlagkratern assozierten strahlinduzierten Mikrogefüges von Zielen und Hohlladungen aus Kupfer
1997
15 Seiten, 12 Bilder, 30 Quellen
Article (Journal)
English
Predicted crater depths under hypervelocity impact
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