Spall properties of Al 5083 plate fabricated using equi-channel angular pressing (ECAP) and rolling

Abstract

The spall strength and Hugoniot Elastic Limit (HEL) of aluminum alloy 5083 (Al 5083) are compared for plates fabricated using equi-channel angular pressing (ECAP) and rolling. Al 5083 is a light-weight and strain-hardenable aluminum alloy used for armor plating in military transport vehicles, thus requiring the highest achievable spall strength and HEL. Materials that were processed by ECAP displayed a highly refined grain structure with little texture and a large degree of plastic deformation, whereas subsequent rolling resulted in a textured microstructure with both grains and inclusions aligning along the rolling direction. The spall behavior of Al 5083 was determined using plate-impact gas-gun experiments with rear free surface velocity measurements for a variety of processing conditions involving both ECAP and rolling. The spall strength and HEL increased from that of the as-received material after processing with ECAP. Subsequent rolling further increased the HEL but reduced the spall strength. Rolling also resulted in directional dependence of the spall strength, with the lowest spall strength occurring for impact through the plate thickness and highest spall strength in the rolling direction. The trends in the spall behavior correlate with the size and preferential alignment of manganese dispersoids and iron and silicon rich inclusions that are evolved during processing.