Re: Are brass and aluminum compatible?
The guy at the store was right and wrong.
Generally speaking, you shouldn't have a problem combining select stainless alloys with most aluminum alloys. The problem is that the use of pure metals is extremely rare. Most are alloyed with multiple elements so you have to look at all the elements in the mix to determine their compatibility.
Case in point, 6061 aluminum. While pure aluminum (1100 alloy) is high up the nobility table, 6061 (aircraft aluminum) is alloyed with copper to improve machining. Copper can be highly reactive to other common alloying elements under a lot of conditions. Big problems typically arise when you when you throw heat and moisture into the mix.
In your situation, assuming that the aluminum is a 5XXX series marine alloy, 3XX or 4XX series stainless hardware would provide satisfactory performance. A high chromium steel alloy would be ideal. Stay away from copper and brass if you don't like little piles of white dust (corrosion) growing from the contact area. Also be mindful of what "anti-seize you use, if any. Most are copper based which only exasperates the problem. The liberal use of a good quality grease on assembly, I prefer calcium sulfonate in marine applications, will go a long way towards minimizing problems in the future.
