The influence of loading rate on shear deformation behaviour of tungsten composite

This paper aimed to study 93% W-4.54% Ni-2.46% Fe tungsten composite loaded at high strain rates ranging from 2200 s(-1) to 4200 s(-1) in simple shear by means of a torsional split Hopkinson bar. The flow stress and stress-strain response are measured by a proposed method. The strain rate sensitivities and deformation mechanism are also investigated with macroscopic results. Compared with those of low strain rate tests performed at 4 x 10(-3) s(-1), the results showed that the flow stress, strain rate sensitivities and deformation mechanisms of tungsten composite are strongly sensitive to strain rate. Microstructural observations revealed by quantitative metallographic techniques found that the deformation of tungsten grains varied with strain rate levels and that microcracks are visible under dynamic loading conditions. Fracture appearance is analyzed by a scanning electron microscope (SEM) to find out the reason why both the binding strength between the tungsten grains and the binder phase, and the fracture characteristics change with increasing loading rate.