Influence of microstructure and strain rate on adiabatic shearing behavior in Ti-6Al-4V alloys

Adiabatic shearing behavior of Ti-6Al-4V alloys with bimodal and lamellar microstructures is investigated at strain rates ranging from 10(3) s(-1) to 10(4) s(-1) by Spilt Hopkinson Pressure Bar and Taylor impact. The characteristic of fracture is closely related with the behavior of adiabatic shear band in Ti-6Al-4V alloys. In bimodal microstructure at strain rate of 10 3 s(-1), the adiabatic shear bands are regularly spaced and orientated along the maximum shear stress plane. In case of the lamellar microstructure, when the strain rates increase from 4000 s(-1) to 6000 s(-1), the adiabatic shear bands go through the transition from self-organization to branching off and interconnecting into a net-like structure. At strain rate of 10(4) s(-1) by Taylor impact, the regularly spaced adiabatic shearing cracks cause that the fracture surface makes an an angle of 45 degrees with the impacted end of the projectile in bimodal microstructure. The net-like adiabatic shearing cracks in lamellar microstructure result in the fragmentation of the projectile head, the angle is about 0 degrees. (c) 2008 Elsevier B.V. All rights reserved.