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Stainless steel seized with aluminum after corrosion test for automotive industries

We recently have a problem which we think it may be due to a galvanic reaction. A stainless steel 416 fitting was interface with an Aluminum ABS module. After corrosion test, male fitting was seized and cannot be removed or removed at high force. Do you know why? Thanks in advance.

Name redacted at writer's request
Ontario, Canada

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But I am not at all surprised that aluminum would corrode under these conditions. Further, I would expect aluminum and stainless to seize anyway.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
 

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Given the dissimilar metals, electrolyte (the corrosion testing solution), and capillary action between the parts, I think you're right on in thinking you have a galvanic cell. If changing materials of the parts is out of the question you may want to try a corrosion inhibitor that can be applied to the mating surfaces to inhibit both capillary action and corrosion. You'll still have the galvanic cell but the inhibitor will keep corrosion to almost nothing as long as it's present.

Jeff Watson
- Pearland, Texas