Stress corrosion monitoring of 7000 series aluminium alloy welded specimens using acoustic emission

Abstract

Acoustic emission (AE) was continually monitored during stress corrosion tests on weldable aluminium alloys (7000 series) supplied by the Defence Research Agency of the UK Ministry of Defence to progress the investigation and understanding of stress corrosion in differently treated aluminium alloys. The welded structures were exposed under known stress conditions to two corrosive environments (marine and humid). The monitored AE activity enabled the crack initiation and propagation associated with stress corrosion cracking to be detected. The different nature of the two environmental conditions to which all of the aluminium alloy specimens were exposed under load greatly influenced the stress corrosion cracking propensity of the alloys. The humid environment was found to be more aggressive than the marine environment, resulting in more rapid crack initiation and failure within the alloys tested. It was concluded that differences in alloy composition and surface treatment had a profound effect on the monitored AE activity during stress corrosion tests.