The dependence of acoustic emission on strain rate in 7075-T6 aluminum

The dependence of RMS acoustic-emission output on strain rate was determined during tensile tests on 7075-T6 aluminum over a range of strain rates from 0.015 min^?1 to 0.230 min^?1. A special normalization technique was developed to eliminate the inherent differences in the acoustic emission from supposedly identical specimens tested under identical conditions. It was found that the RMS acoustic-emission output increases approximately linearly with strain rate, and that the slope of the linear dependence decreased with increased plastic strain. The effect of pinned dislocation breakaway on the acoustic-emission output vs. plastic-strain relationship is the subject of a preliminary theory.