Abstract: The anti-penetration experiments of composite targets with different structures were carried out to study the influence of the arrangement of armored steel in multi-layer heterogeneous composite target on the microscopic mechanism and force state of plastic deformation. The microscopic mechanism of plastic deformation of bullet holes in armor steel is studied based on the theory of metal materials science. The surface hardness distribution and microstructure evolution of armored steel craters are analyzed. The internal relation between the mechanical behavior and deformation mechanism of projectile penetrating into the armored steel is studied through numerical simulation. The results show that the wave impedance matching is from high to low, the stress wave generated by projectile impact is reflected from the interface between the layers, resulting in the formation of a tensile wave and the crack propagation to reduce the projectile penetration resistance; the internal structure of adiabatic shear zone is affected by temperature and extrusion load, producing high-hardness martensite grains and hindering continued plastic deformation; and the higher the strength and stiffness of armored steel backplanes are, the more is the dislocation movement caused by plastic deformation of armor steel hindered, which is conducive to improve the penetration resistance of target plate. Key

Key words: compositetargetplate, penetration, plasticdeformation, microscopicmechanism