Research on the self-sharpening characteristics of WC-Co alloy projectile core during penetration

Abstract

Numerous researchers are seeking methods to enhance the penetration power of tungsten alloy long-rod projectiles, and generating “self-sharpening” in the head of projectile core during penetration is an effective solution. Previous studies found that 88 wt% WC-Co (tungsten‑cobalt cemented carbides) alloy formed smaller ballistic holes compared to conventional 93 W alloy during high-speed penetration test. It is commonly believed that penetrators with self-sharpening characteristics resulted in smaller hole diameters after penetration. This study selected 94 wt% WC-Co alloy and 88 wt% WC-Co alloy for comparative research. Two alloys were subjected to quasi-static, dynamic (SHPB) compression tests, and high-speed penetration tests. The specimens and residual projectile cores were systematically analyzed using scanning electron microscopy (SEM). The results showed that both alloy specimens were crushed, and the quasi-static compressive yield strength of 88 wt% WC-Co alloy was 3.42 GPa. As the fracture angle (angle between the top surface and the fracture surface) increased, the fracture mode gradually transitioned from transgranular to intergranular fracture, with observations of the lubricating characteristics of Co phase, and the fracture angle after SHPB tests basically exceeded 45°. The quasi-static compressive yield strength of 94 wt% WC alloy was 4.15 GPa, and after quasi-static/dynamic compression, the specimens developed longitudinal cracks from front to back, primarily in an intergranular fracture mode. After high-speed penetration tests, it was observed that the projectile cores made from both alloys demonstrated self-sharpening characteristics during penetration, achieved through material fragmentation and lubrication by Co phase. This study provides reference for further research on the self-sharpening characteristics of WC-Co alloy penetrators.