Fatigue strength reduction from sulfuric acid anodizing
Dear Fellow Finishers:
While I believe it is generally known that sulfuric acid anodize will/may cause a reduction in the fatigue strength characteristics of aluminum alloys. I would appreciate it if someone could supply me with an actual reference which documents this. A reference with test data would be even more helpful.
Thank you in advance for your help.Blair Smith
aerospace - Windsor Locks, Connecticut
Blair, Check out "The Technology of Anodizing Aluminum" [link is to info at Amazon about the book] by Brace and Sheasby. Also look at volume two of "The Surface Treatment & Finishing of Aluminum and its Alloys" by Wernick, Pinner and Sheasby. Mr. Brace is in England. Probably worth contacting if the several references in the two books do not satisfy your needs.
In short, it is a mixed bag with conflicting research. I think that your sister company PWA is close to paranoid about it on vanes, or at least the stripping and preprocessing steps.James Watts
- Navarre, Florida
I know of no aircraft company that allows sulphuric anodising on critical parts . You would lose the crack detection , and it would be disastrous if used on an assembled part . Think of what would happen to the slip rings on a 23 E 50 prop blade in sulphuric acid .Dave Brackenridge
aerospace plating - Germiston, South Africa
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