Metallographic Observations of Rolled-Homogeneous-Armor Specimens From Plates Perforated by Shaped Charge Jets

In each of a series of experiments, a plate of rolled homogeneous armor (RHA) is perforated by a copper jet from a shaped charge warhead. Microscopy specimens of RHA are prepared from a remaining, perforated target plate and from various recovered fragments. Optical and scanning electron microscopy reveal shear bands, voids, cracks, and evidence of precipitate formation and microstructure transformation in the original martensite. Some shear bands contain a finer-scaled microstructure than that of the ambient martensite, while others contain martensitic laths of dimensions similar to those of the ambient martensite. Cracks in RHA specimens are generally associated either with shear bands or with coalescing voids. In a specimen from a copper fragment, a variety of grain sizes and extensive twinning are observed.