Tailoring the adiabatic shear susceptibility of pure tungsten via texture evolution

Pure tungsten (W) is generally believed to be a preferred alternative material for kinetic penetrators once a “self-sharpening” effect can be realized by inducing adiabatic shear failure during high-speed impact. However, it is still a major challenge to trigger adiabatic shear bands (ASBs) in pure W with low ductility. In this work, we reported an improved adiabatic shear susceptibility of pure W by controlling the texture evolution during the pre-rolling process. As the rolling strain increased, the texture components and intensity underwent crucial variations to facilitate the appearance of ASBs. For comparative studies, we investigated the dynamic behavior of three kinds of W samples with different microstructural features at a wide range of temperatures (298K∼1473K) via SHPB system, including coarse-grained W (CGW), as-rolled W samples to the thickness reductions of 75% (75W) and 80% (80W). The experimental results revealed a transition of failure behavior from typical brittle fracture to adiabatic shear instability under uniaxial dynamic compression. Of particular interest was that although 75W and 80W exhibited almost the same mechanical properties after the similar rolling reductions, their dynamic instability behaviors differed remarkably with different spatial distributions of texture components. In the as-rolled 75W, two dominant texture components of {001}<110> and {111}<110> were alternate to form fully spaced layers. Under uniaxial compression, the {111}<110> “hard orientation layers” became the obstacles to the propagation of ASBs. Fortunately, in 80W specimens the different {001}<110> “soft orientation layers” were interconnected by the “soft bricks” of the same orientation, which provided pathways for the expansion of shear localization and ultimately the triggering of ASBs. Through subsequent crystal plasticity finite element (CPFEM) simulations, we further verified the effect of orientation distributions on the shear localization and thoroughly explained the formation mechanism of ASBs in the highly textured refractory metal. This may provide guidance for producing advanced materials for certain practical applications.