22. Microstructural Effects on the Spall Properties of 5083 Aluminum: Equal-Channel Angular Extrusion (ECAE) Plus Cold Rolling

5083 Aluminum alloy is a light weight and strain-hardened material used in high strain-rate applications such as those experienced under shock loading. Symmetric real-time (in-situ) and end-state (recovery) plate impact experiments were conducted to study the spall response and the effects of microstructure on the spall properties of both 5083-H321 and 5083-ECAE + 30 % cold-rolled (CR) aluminum alloys shock loaded to approximately 1.46 GPa (0.2 km/s) and 2.96 GPa (0.4 km/s). The results show that mechanically processing the 5083-H321 aluminum by ECAE, followed by subsequent rolling significantly increases the Hugoniot Elastic Limit (HEL) by 78 %. However, this significant increase in HEL was at the expense of spall strength. The spall strength of the 5083-ECAE + 30 % CR aluminum dropped by 37 % and 23 % when compared to their 5083-H321 aluminum counterpart at shock stresses of approximately 1.46 GPa (0.2 km/s) and 2.96 GPa (0.4 km/s) respectively. This reduction in spall strength is attributed to the re-alignment of the manganese (Mn)-rich inter-metallic second phase particles during mechanical processing (i.e., ECAE and subsequent cold rolling) which are consequently more conducive to spallation.