Corrosive properties of Stainless Steel contacting aluminum 6061
Corrosive properties of Stainless Steel contacting aluminum 6061
(OP)
During some recent "re-work", a fellow engineer at our company discovered corrosion on stainless steel screws that were removed from threaded holes that were tapped in aluminum 6061. MOST all of the hardware we build is machined out of 6061, and most ALL the fasteners we use are stainless steel. Upon his discovery, we have adopted the policy of coating ALL contact areas of stainless and 6061 including threads and fastener head contact areas with zinc chromate primer. However, it is not always "convenient" to use this. We are looking for other alternatives. Has anyone else discovered this corrosion between stainless and 6061? We realize that we could eliminate the problem if we had cadmium coated screws, but we also realize how difficult they are to procure. Any ideas on alternate methods of approach to solve this problem? By the way, the 6061 is typically sent thru a chromate conversion (iridited) such as Mil-C-5541.





RE: Corrosive properties of Stainless Steel contacting aluminum 6061
Regards,
Cory
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: Corrosive properties of Stainless Steel contacting aluminum 6061
RE: Corrosive properties of Stainless Steel contacting aluminum 6061
My guess is that it is crevice corrosion. The Al corrodes slightly, then the Al oxide traps moisture and chlorides, and then the stainless corrodes.
You might have better luck sealing the joints.
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Corrosion never sleeps, but it can be managed.
http://www.trenttube.com/Trent/tech_form.htm
RE: Corrosive properties of Stainless Steel contacting aluminum 6061
RE: Corrosive properties of Stainless Steel contacting aluminum 6061
So, what was the final conclusion? A marine environment? It hardly seems that given the choice for corrosion to work it would go after CRES when their is tasty Al in the same area.
RE: Corrosive properties of Stainless Steel contacting aluminum 6061
RE: Corrosive properties of Stainless Steel contacting aluminum 6061
RE: Corrosive properties of Stainless Steel contacting aluminum 6061
RE: Corrosive properties of Stainless Steel contacting aluminum 6061
RE: Corrosive properties of Stainless Steel contacting aluminum 6061
For anodic reasons, can you add a chunk of zinc with a mechanical fastener anywhere? This solved a lot of problems for us because our product became the ground for any stray current and started "releasing" aluminum from our structure.
RE: Corrosive properties of Stainless Steel contacting aluminum 6061
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Regards,
Cory
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: Corrosive properties of Stainless Steel contacting aluminum 6061
My 2-cents worth...
I posted comments on a very similar topic, located on Thread338-110764.
After reading the thread, ask me if I'm paranoid about Aluminum-CRES dissimilarity... and about the use of grease for corrosion protection.
Regards, Wil Taylor