Failure mechanisms in ballistic performance of Ti–6Al–4V targets having equiaxed and lamellar microstructures

• The relationship between failure mechanism and microstructural features of the Ti-6Al-4V targets was established.
• Ductile hole enlargement was observable in targets having equiaxed microstructure.
• Brittle fragmentation was observable in targets having lamelalr microstructure.

The relationship between the failure mechanism and the microstructural features of the Ti–6Al–4V targets was established in this paper. The 12.7 mm armour piercing (AP) projectiles were fired against the Ti–6Al–4V targets having equiaxed and lamellar microstructures with thickness ranging from 30 to 45 mm. Ductile hole enlargement characterized by delamination and spall fragments from the rear surface was observable in the Ti–6Al–4V targets having equiaxed microstructure, while brittle fragmentation characterized by plugging and star fragments from the rear surface was observable in the Ti–6Al–4V targets having lamellar microstructure. The distinctly different propagating features of adiabatic shear bands in Ti–6Al–4V targets having equiaxed and lamellar microstructures determined the failure mechanism analyzed. In the equiaxed microstructure, the regularly spaced propagating features of adiabatic shear bands facilitated the failure mechanism of ductile hole enlargement. In the lamellar microstructure, the net-like propagating features of adiabatic shear bands facilitated the failure mechanism of brittle fragmentation.