The mechanical response and failure mechanism of a near α titanium alloy under high-strain-rate compression at different temperatures

Abstract

Abstract High strain rate compression of Ti-60 titanium alloy with equiaxed structure were performed from 25 °C to 400 °C at strain rates of 1500s−1 and 3000 s−1 by means of the split-Hopkinson pressure bar technique. It was found that the increasing temperature induced the decrease of flow stress and the drop in the yield stress for Ti-60 alloy. The adiabatic shear bands (ASBs) led to a slight flow softening when the sample was not broken. Recrystallization grains with average grain size of 1 μm were found in the ASBs. An original method basing on the elongation of equiaxed α phases was proposed to estimate the true shear strains in the ASBs. On such a base, the dynamic recrystallization (DRX) in the ASB was well explained by the rotational dynamic recrystallization (RDR) mechanism. The Johnson-Cook model was established to be applied to the FEM (finite element method) analysis. It showed that the higher strain and strain rate at different direction would induce the branching ASBs of specimen. Mechanical analysis of the branching ASBs showed that macroscopic cracks were prone to initiating and propagating at the intersection of different ASBs because of component force perpendicular to the ASB.