Correlation of adiabatic shearing behavior with fracture in Ti-6Al-4V alloys with different microstructures

The correlation of adiabatic shearing behavior with fracture was investigated in Ti-6Al-4V alloys with bimodal and lamellar microstructures by split Hopkinson pressure bar (SHPB) apparatus and ballistic impact test. The experiment results show that the macrographic characteristic of post-critical fracture is closely related with the behavior of adiabatic shear band (ASB) in these titanium alloys under high strain rate conditions. In bimodal microstructure, adiabatic shear bands are self-organized and distributed in somewhat regularly spaced clusters. These adiabatic bands as well as the correlated cracks spread far off along the maximum shear stress plane, which causes the projectiles fracture along the dominant cluster of adiabatic shear bands, and the fracture surfaces make an acute angle with the flat end of the projectile. In case of lamellar microstructure, the adiabatic shear bands branch off and interconnect with one another into a net-like structure. Such adiabatic shearing cracks can't spread deep resulting from the branching off and interaction of adiabatic shear band, but only to split the specimen into small fragments, which leads to the erosion of the projectile and the resulting fracture surfaces almost parallel to the flat end of the projectile.