2195 Al-li Alloy Adiabatic Shearing Sensitivity And High Speed Penetration Behavior Research

The adiabatic shear susceptibility of2195aluminum-lithium alloy were investigated by means of split Hopkinson pressure bar. The stress collapse in true stress-true strain curves and true stress-time curves were observed which meant adiabtic shear bands appeared in materials. The adiabatic shear susceptibility of different aging statuses and strain rate were discussed by means of metallography observation, comparing the critical strain and stress collapse time of stress collapse and formation energy of adiabatic shear bands. The results show that different aging statuses and strain rate have significant influences on adiabatic shear behaviors of2195aluminum-lithium alloy. The peak-aged specimen has the highest adiabatic shearing susceptibility, while the under-aged specimen has the least adiabatic shear susceptibility. The adiabatic shear susceptibility increases with the increases of strain rate.The hypervelocity penetration of2195aluminum-lithium was investigated by two-stage light gas gun. The micro-damages were observed by optical microscope. A hemispherical crater forms in the front surface of target, a value of H/D is gradually close to0.5with increasing impact speed. The bottom of crater is smooth when impact speed is low. When impact speed reaches to4.6km/s, many thin delaminated sheets and a large amount of fragmentation are observed in the hypervelocity impact region. The length of adiabatic shear band in target increases with increasing kinetic energy of projectile. The optical micrograph indicates that micro-cracks nucleate and propagate along grain boundary more easily.Hypervelocity penetration behavior was investigated through finite element software. The simulational results show that the volume of crater is proportional to the kinetic energy of projectile. Simulational errors tend to increase with increasing impact velocities. The distribution of maximum shear stress and temperature of target were discussed. To investigate stress and temperature variations about secondary phase particles during penetration, a non-uniform mode was established. Stress concentration happens at secondary phase particles in target and temperature risen is higher than matrix.