Dynamic mechanical properties and adiabatic shearing behavior of the shock prestrained Ti–6Al–4V alloy having bimodal microstructure

Abstract

Plate impact experiments and dynamic reloading compression tests at 3 × 103 and 4 × 103 s−1 were conducted on the Ti–6Al–4V alloy with bimodal microstructure to investigate the effect of shock prestrain on the dynamic mechanical properties and adiabatic shearing behavior of this alloy. The shock prestrained alloy has higher flow stress but lower uniform plastic strain and impact absorption energy at both reloading strain rates due to the multiplication of dislocations during shock pulse. The Bauschinger effect and the lack of more effective strengthening factors limit the shock-induced strengthening effect in Ti–6Al–4V at an equivalent strain level during reloading at a strain rate of 3 × 103 s−1. However, the shock-induced strengthening effect is somewhat improved at a higher reloading strain rate. Shock prestrain facilitates the formation, bifurcation and interaction of adiabatic shear bands (ASBs) in Ti–6Al–4V through the promotion of the dynamic recovery process at the primary stage of the formation of ASBs. Plugs and clusters of ASBs can form in the shock prestrained Ti–6Al–4V with bimodal microstructure at a relatively low strain rate due to the high density and frequent interactions of ASBs.