Study on ballistic impact behavior of Al alloys against two different shapes of steel core projectiles

Abstract

In this study, a relation between the quasi-static, dynamic compressive and ballistic impact of 7055 and 7075 Al alloys was made. The results showed that the ultimate tensile strength, hardness and absorption capacity were considerably higher in 7055 Al alloy compared to 7075 Al alloy. Consequently, 7055 Al alloy exhibited superior ballistic impact resistance (low depth of penetration) against different shapes of 7.62 mm soft steel core projectiles. The microstructure evolution after ballistic impact revealed gradient variation of strain rate away from the crater which assists in the nucleation of different deformation zones, i.e., fine grain zone (FGZ), high-density deformation zone (HDZ) and low-density deformation zone (LDZ). These zones were confirmed through optical micrographs, hardness, stress-strain and XRD analysis. The strong texture {111} component was changed to the {111} and {200} component in HDZ and LDZ, which also assists in understanding that the deformation was more complex in these regions. Therefore, a model was proposed for the nucleation of fine grains near the crater. In addition, fracture morphology was different under each loading condition and a transitional effect is observed from quasi-static loading to ballistic impact loading. These interesting features can further enhance the understanding and the development of Al alloys in aerospace and military applications.