Ti-6Al-4V在高应变率下的动态剪切特性及失效机理

Dynamic shear properties and failure mechanism of Ti-6Al-4V were studied at strain rates in excess of 10⁴ s^-1, with a new loading method based on the split Hopkinson pressure bar (SHPB) technique. The shear stress-shear strain curves and failure parameters of Ti-6Al-4V were acquired in a wide range of high shear strain rates. It is found that the flow stress of the material shows an obvious strain rate hardening effect. With the increase of strain rates, the failure stress of the material increases gradually, while the failure strain decreases. The loading process was modeled by ABAQUS/Explicit software. The results show that the shear zone material is substantially in the state of plane shear. The tested stress-strain curves have good agreement with the simulated results. The fracture surface examination shows that with the increase of strain rate, the failure of Ti-6Al-4V is closely related to the different behaviors of dimples, and it indicates an evolution process from dimples and tensile dimples to steps and river patterns. The fracture analyses show that the failure mode of the material is mainly ductile fracture.