Hypervelocity impact into a high strength and ductile steel alloy

The unusual properties of nitrogen alloyed austenitic steels have been reported in the recent two decades in many papers. In this work it is aimed to investigate a P900 alloy subjected to a hypervelocity impact. The P900 alloy was work hardened to a medium hardness of 380 HV30 by cold expansion of a ring. Tungsten heavy metal and pure tungsten were used as projectile materials. The geometry of the long rods was 3 mm x 30 mm for diameter and length, respectively. Ballistic tests were performed with a two-stage light-gas gun at velocities from about 2000 m/s up to about 4500 m/s. It was found that two kinds of crater geometry are possible depending on the tendency of the projectile material to adiabatic shear banding or brittle fracture. The brittle W material achieved a deeper crater than the shear band forming W heavy alloy. (C) 2008 Elsevier Ltd. All rights reserved.