Dynamic shear deformation and failure of Ti-5Al-5Mo-5V-1Cr-1Fe titanium alloy

To study the high strain rate shear behaviour of Ti-5Al-5Mo-5V-1Cr-1Fe (Ti-55511) alloy, dynamic compression tests of hat shaped specimens have been conducted using a split Hopkinson pressure bar. Localized shear deformation is induced in Ti-55511 alloy by subjecting it to high local shear strain rate under dynamic compression tests. The experimental results demonstrate that: a) for a certain range of the velocity of the striker bar, the shear stress and local shear strain rate are independent on the applied force; b) no α→β phase transformation occurs in the localized shear region, and the formation of a shear band does not mean the occurrence of phase transformation; c) the microhardness within the shear band is lower than that of the matrix area and the region close to the shear band, and the microhardness in the bottom region of the shear band is lower than that of the top region; and d) brittle shear bands without microvoids and microcracks are observed for Ti-55511 alloy.