If you need to know about long term effects of CRES and aluminum especially in a salt (i.e. marine environment) you should consult the any number of technical manuals put out by the U.S. Navy and the various Marine Engineering Institutes. There are a lot of factors you don't mention.
1. Which alloy of austenetic stainless? 2. Which alloy of Aluminum? 3. Is it possible to use ALCLAD or equivalent? 4. Will it be in water or air or both? 5. If in water will it be in a static or flowing type of environment. 6. Will the water be oxygenated or not. Are there any other chemicals expected in the water. 7. If in atmosphere what are the humidity and temperature ranges like? Any chemicals in the air. For instance lots of smog or stack gases. 8. If in both you are in real trouble. Marine engineers have looked at and/or solved all of these problems. Also Navy and Civilian Nuclear Engineers can tell you a lot about galvanic corrosion in a lot of liquid and liquid/air envirorment. In a general way if the materials are separated by a good insulator (plastic, rubber, dry air, distilled water, etc.) of sufficient thickness/distance galvanic corrosion won't be a problem. Otherwise the aluminum will corrode like crazy unless treated in some way. Given a sufficiently corrosive atmosphere and or conditions the CRES will corrode also. The austenetic series (the so called magnetic stainless steels) typically behave more like highly resistant mild steels then the more exotic alloys like Inconel, 17-4 PH, or the various copper/nickel alloys. The more exotic aluminum alloys tend to be more corrosion resistant as does pure aluminum. Unfortunately for exotic read expensive. Pure aluminum, while very corrosion resistant is not very good as a structural material. There is a lot of material out there to study if you need it especially long term stuff concerning the joining of aluminum superstructures to steel hulls in the various Marine/Naval Engineering Journals. Hope this helps Jack Gypin == Sic transit gloria mundi, and Tuesdays are usually worse! _________________________________________________________ DO YOU YAHOO!? Get your free @yahoo.com address at http://mail.yahoo.com
