Response of hot isostatically pressed Ti-6Al-4V targets to normal impact by conical and blunt projectiles

摘要

First experimental results are reported on ballistic performance of hot isostatically pressed (HIPed) texture-free targets using rapidly solidified powders of Ti-6Al-4V alloy (PREP and ELI-PREP). Plastic deformation by ball milling of these powders was performed to modify the microstructure of the materials. HIPed samples of 40mm diameter and a thickness of 10-30mm were shrinkfit into holes in larger diameter steel plates and struck by 50 caliber 60° cylindro-conical projectiles of hardness R_c 60 with contact produced either by the conical or blunt surface. The mass of the projectile was about 31g and the initial velocities ranged from 300 to 450m/s for flat-ended and from 900 to 950m/s for the conical impacts. Comparative behavior of HIPed samples and standard samples made from commercially available Ti-6Al-4V alloy MIL-T-9047G (bar, forged, annealed)―baseline material after impact with the same geometry was investigated. As a rule the final velocity of the plug for HIPed alloy was smaller (or no penetration was observed) than that of the baseline material for impact with the conical projectile. Slightly sloped cylindrical shear plugs were characteristic for both materials upon impact by flat projectiles and their velocities were used to evaluate the shear resistance of HIPed material to plugging. Comparative features of fracture in both cases are presented. The texture-free HIPed materials from powders demonstrated better ballistic performance than the baseline material and could be successfully used for ballistic applications. This is the first step in the development of high-gradient composite materials using a Ti-6Al-4V matrix from powder.