Monitoring Stress-Corrosion Cracking by Acoustic Emission

Abstract

Acoustic emission (AE) is well suited for laboratory studies of stress corrosion cracking (SCC) since the crack velocity is often approximately proportional to the AE rate. For 7075-T651 and 2024-T351 aluminum alloys, this proportionality is shown to be particularly good. For 7075-T651, less scatter is obtained in SCC crack velocity when these are based on the cumulative AE counts than on surface crack length measurements. The curve of AE rate versus time after addition of fresh solution into the crack depends on the type of transducer employed. Using either a broad-band or a resonant transducer, it was possible to distinguish between SCC and corrosion signals from their frequency spectrum. The applicability of employing AE to detect SCC in an industrial environment is considered. Possible solutions to some of the difficulties expected in cases where SCC produces low-amplitude AE signals are discussed.