The effects of bimodal microstructure characteristics on susceptibility to adiabatic shear bands of modified Ti-6AI-4V alloys

This work reported an examination about the effects of bimodal microstructure characteristics on the susceptibility to adiabtatic shear bands for modified Ti-6A1-4V alloys subjected to high-strain-rate deformation. The obtained microstructures with different bimodal characteristic parameters under different heat-treatment conditions underwent dynamic shearing experiments using the technology of Split Hopkinson Pressure Bar. The results indicate that the volume fraction of primary alpha phase is reduced and that of secondary alpha phase precipitated within the beta matrix increases with increasing the solution temperature. When the solution temperature exceeds 860°C , the size of secondary alpha phase significantly increases. It is found that a large number of precipitated thin secondary alpha phase distribute dispersedly within the beta matrix at 860°C , while it keeps a relatively lower number of secondary alpha phase at other solution temperatures. Correspondingly,the possibility of local enormous plastic deformation is reduced due to the significant increase of alhpa/beta phase interfaces. Hence, the bimodal microstructure treated at 860°C show the least susceptibility to the adialbatic shear bands.