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Originally Posted by Epepperman
Speaking of the possible galvanic action of stainless and aluminum...
What is our firewall made of again, and what fasteners do we use to rivet them on with? Is this really an issue?
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If it is an issue or not depends on where you are going to fly. Galvanic corrosion problems in aluminum is generally no issue at all, or only a minor issue. However, in marine environments, galvanic corrosion problems is THE issue of ALL corrosion issues. This is common knowledge to every boat owner (salt waters), and to the
US Navy.
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An estimated 90% of corrosion damage to our F/A-18 aircraft is due to galvanic interactions
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The point is that galvanic corrosion, if left to develop, can destroy parts within a few months close to the sea, days even. Still, only a few miles inland and the problem is non existent.
The combination of aluminum and stainless is a special case, this combination is 100% safe away from the sea (no salt). These alloys will not interact in fresh water environments even though the galvanic potential between them is larger than aluminum and copper. In a marine atmosphere they will interact instantly where aluminum will corrode rapidly.
Besides, 301 stainless will not last long in a marine environment if left untreated, passivated or not. It is definitely not a metal you would ever put on the deck of a boat (316 stainless and lots of other alloys are made for marine use). Untreated 6061 aluminum will last for years and years in marine environments, but connect it with a piece of 301 stainless and corrosion starts within days. I have a test piece of 6061 riveted with 304 stainless using various protection methods that will be permanently fitted to my boat for some years, just to see how it develops.
Corrosion of aluminum is entirely decided by the environment. Practically speaking it is a problem that exist exclusively for marine environments. Inland, the problems are virtually non existing.