Measurement of Elastic and Plastic Unloading Wave Profiles in 2024‐T4 Aluminum Alloy

Velocities for one‐dimensional release waves in 2024‐T4 aluminum alloy have been obtained between 30 and 132 kbar. Stress‐time records were obtained with piezoresistive manganin gauges. The release wave clearly showed the existence of two release systems. The leading edge of the release wave was 27% faster than the bulk sound velocity calculated from the ideal fluid model. The second release system was identified by a change in slope of the release wave profile. The peak velocity of this release system did correspond more closely to the hydrodynamic bulk sound velocity. These results imply elastic behavior of aluminum at high pressure. The shape of the release wave, however, cannot be fitted by a perfect elastic‐plastic model, thus pointing out the need of a more elaborate description.