Investigation on the influence of electrospark deposited 718 alloy coating on the penetration performance of 93 W rod

Abstract

A ballistic experiment on a semi-infinite RHA target impacted by two thicknesses clade 93 W rods (200 μm 718 alloy and 400 μm 718 alloy) with an impact velocity of 1500 ± 50 m/s is conducted to investigate the influence of 93 W surface deposited coating on penetration performance. Moreover, the findings are compared with those of an unclad 93 W rod. This study aims to provide a comprehensive microstructural overview of the penetration process, including the solid-state penetrator flow and the exchange interaction mode of rod and target (R.T.) materials, using optical metallography and electron microscopy. Results indicate that the coating area is composed of approximately equiaxed or short columnar cellular crystals. Furthermore, a metallurgical fusion layer is formed between the substrate and the coating, ensuring excellent bonding strength of the coating. No significant difference in the rheological mode is found between the interfaces of the 200 μm 718 alloy and 93 W R.T. materials, while the 400 μm 718 alloy forms a barrier mix zone at the interface between the R.T. This phenomenon alters the exchange mode of the target material and affects the interface flow mechanism. The barrier mix zone also acts as a solid-state lubricant at the interface, reducing the resistance to the rod's penetration. The average penetration depth of the 400 μm clad rod is 6.89 % higher than that of the 93 W rod. This finding reveals the clad material enhances the rod's performance and provides self-lubricating characteristics.