Processing, high-strain-rate properties and ballistic performance of hot isostatic pressed titanium-aluminum-vanadium based homogeneous and high gradient composite armor materials

Hot Isostatic Pressing (HIP) was first used to manufacture ballistic grade Ti-6Al-4V alloy and high gradient composites incorporating Al2 O3 rods, plates and tubes filled with B4C powders. Processing parameters were investigated and optimized based on materials properties.;Chemical and phase composition, elastic properties and microstructural characteristics were considered to establish correlation with dynamic properties. Military grade baseline Ti-6Al-4V (MIL-T-9047G, forged, annealed) material with excellent combination of strength and ductility was selected for comparison with powder-based materials.;First, results were obtained on high-strain rate properties of this Ti-6Al-4V alloy. Hopkinson bar tests showed lower ductility in HIPed material in comparison with baseline material. Strain-controlled compression tests revealed that HIPed material nucleate shear bands at smaller strains and have a lower failure strain. Hat-shaped specimen tests demonstrated that both materials have similar shear strength and energy dissipation in single "forced" shear band. Texture effects caused by alignment of microstructrual constituents were investigated in the Hopkinson bar tests for the baseline material. This property may partially affect ballistic performance.;Thick wall cylinder (TWC) tests were used to reveal different shear band patterning (an important characteristic of post-critical behavior) in baseline and powder-based materials. Different shapes of voids in those materials were noticed as another feature developed during the failure process. An approach was proposed to explain correlations between material micro & macro properties and ballistic performance. Three different ballistic tests (flat-ended projectile impact, conical projectile impact and long rod projectile impact) at a velocity range of 300∼1000 m/s were conducted to investigate ballistic performance. It was established that HIPed materials have a better penetration resistance compared to the baseline material. High gradient composite materials demonstrated new features of damage patterning during the long rod projectile penetration process. They included projectile deflection, self-sealing of the hole and built-in mechanism of forced shear localization in the direction of 45° to the impact line caused by fracture of Al2O3 tubes on the initial stage of penetration process.;The obtained results prove that powder-based approach can be used for processing of materials suitable for ballistic and other applications, for example, within the biomedical field.