Geometry, mechanical and ballistic properties of ADI material perforated plates

Abstract

In this paper, austempered ductile iron has been evaluated as an alternative to steel for perforated plates applied in the ballistic protection of military vehicles. The austempering was performed in lower and higher austempering ranges in order to obtain two types of austempered ductile iron: one with a higher strength, and the other with a higher ductility. Perforated plates having two different thicknesses of 7 and 9 mm were mounted in front of basic armour and 12.7 x 99 mm armour piercing incendiary ammunition was fired from 100 m. It was shown that the austempered ductile iron material austempered at a lower temperature has superior ballistic resistance, providing a full (five out of five armour piercing incendiary shots stopped) ballistic resistance if combined with 13 mm basic armour plate. The thicker austempered ductile iron perforated plate provides more significant penetrating core damage, and therefore, lower basic plate damage. On the other hand, the thinner austempered ductile iron material perforated plate can be considered optimal due to its lower weight and higher mass effectiveness. In austempered ductile iron material austempered at a higher temperature, besides a lower hardness, bulk retained low-carbon metastable austenite transforms into martensite through strain induced mechanism, causing a partial brittle fracture.