Stress corrosion cracking of an aluminum alloy used in external fixation devices

• Published in: Journal of biomedical materials research. Part B, Applied biomaterials Vol. 86B; no. 2; pp. 430 - 437
• Main Authors: Cartner, Jacob L., Haggard, Warren O., Ong, Joo L., Bumgardner, Joel D.
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 01.08.2008
• Subjects: Alloys - chemistry; Alloys - standards; Aluminum; aluminum 7075; anodization; Body Fluids; Chlorides - pharmacology; Corrosion; Electrochemistry; external fixation; External Fixators - standards; Humans; Materials Testing; Orthopedic Fixation Devices - standards; stress corrosion cracking
• ISSN: 1552-4973; 1552-4981
• DOI: 10.1002/jbm.b.31038

Treatment for compound and/or comminuted fractures is frequently accomplished via external fixation. To achieve stability, the compositions of external fixators generally include aluminum alloy components due to their high strength‐to‐weight ratios. These alloys are particularly susceptible to corrosion in chloride environments. There have been several clinical cases of fixator failure in which corrosion was cited as a potential mechanism. The aim of this study was to evaluate the effects of physiological environments on the corrosion susceptibility of aluminum 7075‐T6, since it is used in orthopedic external fixation devices. Electrochemical corrosion curves and alternate immersion stress corrosion cracking tests indicated aluminum 7075‐T6 is susceptible to corrosive attack when placed in physiological environments. Pit initiated stress corrosion cracking was the primary form of alloy corrosion, and subsequent fracture, in this study. Anodization of the alloy provided a protective layer, but also caused a decrease in passivity ranges. These data suggest that once the anodization layer is disrupted, accelerated corrosion processes occur. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008