A detailed microscopic characterization of stress-corrosion cracking (SCC) processes has been conducted for electro-chemically pitted AA 2024-T3 aluminum dogbone specimens in a high-cycle fatigue environment. The measurements were done in-situ using scanning laser ultrasonic detection of Rayleigh waves propagating along the material surface. Detailed microscopic NDE evaluations of crack extent and position, crack growth rates, and local crack depth were made based on near-field ultrasonic scattering signatures. A variety of electro-chemically generated corrosion pits were studied, where variations of pit depth, pitting surface area, and pit volume loss were correlated to fatigue life, crack initiation, and crack growth rates. The measurement technique provided an advanced crack 'imaging' capability that proved to be a very useful NDE tool for the micro-characterization of crack growth processes, and provided a wealth of information regarding the micro-features of the cracks whcih are currently not available with any other advanced NDE technique.

Date Published: 22 July 2003
PDF: 10 pages
Proc. SPIE 5045, Testing, Reliability, and Application of Micro- and Nano-Material Systems, (22 July 2003); doi: 10.1117/12.483998

Published in SPIE Proceedings Vol. 5045:
Testing, Reliability, and Application of Micro- and Nano-Material Systems
Norbert Meyendorf; George Y. Baaklini; Bernd Michel, Editor(s)