Comparison of the acoustic emission generated by tensile and compression testing of 7075 aluminum

An experimental study of the acoustic emission generated during tensile and compression testing of unflawed 7075 aluminum has been completed. Variables studied included: specimen orientation in a 13-cm plate, 1, 3 and 4.8 percent plastic stretches before the aging heat treatment, and 7075-T6 vs 7075-T651. The level of acoustic emission for strains greater than 1.5 percent was about two orders of magnitude greater in tension than in compression. In the T-6 state the acoustic emission level generated at first macroscopic yielding is about the same in both tension and compression tests. Samples of 7075-T6 can be distinguished from 7075-T651 by the acoustic emission generated during a simple compression test and for both tension and compression tests the acoustic emission is of higher level when the loading axis is perpendicular to the rolling plane.