Microstructural analysis of residual projectiles—A new method to explain penetration mechanisms

Abstract

In the present work it is shown that metallographic analysis can supply a lot of detailed information about metallurgical events which happen during the penetration of metallic projectiles into armor steel. With the help of these findings models of penetration processes are derived. The deformation, fracture, and phase transformation processes of projectiles are investigated, which consist of tungsten, a tool steel, and a tungsten heavy metal, respectively. These were shot into armor steel at velocities between 1000m/s and 2000 m/s. The extensively deformed tungsten and the brittle steel form two opposite poles; between those the heavy metal takes a mid position. The more ductile a material is, the sooner its penetration approaches the piercing of a liquid jet. On the other hand, in a brittle material quick rupture is followed by turbulent motion and friction welding of the fragments. In this case extensive deformation is observed only in the skin layer of a fragment and in shear bands. Special attention is drawn to features which are characteristic for ballistic piercing processes,e.g., molten films and adiabatic shear deformation.