Inelastic deformation and failure of tungsten carbide under ballistic-loading conditions

High-speed photography has been used to investigate the dynamic behaviour of similar grades of WC-Co hardmetals during ballistic impacts with velocities in the range of 28–484 m/s. Key features of the failure of similar grades of WC-Co materials during complimentary impacts have been observed and discussed. In particular, fast moving fragments were observed to emanate from the point of impact and flow radially across the target's surface analogous to the processes of interface defeat. Further, as the velocity of impact was increased a non-linear increase in the indentation depth was observed that corresponded with an apparent onset of trans-granular fracture in the WC crystallites. Comparisons with ANSYS AUTODYN™ simulations were made and good correlation has been established between the measured inelastic deformation and computations using a simple strain-hardening model.

Research highlights▶ Studied a tungsten carbide projectile striking a tungsten carbide target. ▶ Shown that for the given experimental setup, this material is susceptible to interface defeat. ▶ Simulated results using a simple strain-hardening model using AUTODYN™ with good correlation. ▶ Shown that a marked change in indentation depth occurs as the velocity is increased that coincides with extensive trans-granular fracture just below the impact surface. ▶ Estimated the dynamic hardness of the WC-Co and shown that this material's strength is not sensitive to strain rate over the range of experimentation.