Penetration experiments with 6061-T6511 aluminum targets and spherical-nose steel projectiles at striking velocities between 0.5 and 3.0 km/s

We conducted depth of penetration experiments with 7.11-mm-diameter, 74.7-mm-long, spherical-nose, 4340 steel projectiles launched into 250-mm-diameter, 6061-T6511 aluminum targets. A powder gun and two-stage, light-gas guns launched the 0.023 kg projectiles at striking velocities between 0.5 and 3.0 km/s. Post-test radiographs of the targets showed three response regions as striking velocities increased: (1) the projectiles had slight bulges near the nose and some shank bending, (2) the projectiles had large bulges and kinked shanks, and (3) the projectiles eroded and lost mass. For the first response region, penetration depth increased as striking velocity increased. However, when the second region was reached, there was a dramatic reduction in penetration depth. For the third response region penetration depth increased with increasing striking velocity. To show the effect of projectile strength, we compared depth-of-penetration as a function of striking velocity for spherical-nose rods with average Rockwell hardnesses of 36.6, 39.5, and 46.2. To show the effect of nose shape, we compared penetration data for the spherical-nose projectiles with previously published data for ogive-nose projectiles.