![]() ![]() Along the same theme - I am currently restoring my Land Rover Defender, which has an Aluminum body. I would like an explanation as to why this is, nevertheless, acceptable. Yet, this would appear to be a clear case of dissimilar metal contact, resulting in galvanic corrosion over time. It is considered acceptable to swage 21-6-9 steel fittings on 6061-T6 aluminum tubing. My question pertains to the external swaging technique of fittings on tubing in aerospace applications. The galvanic corrosion issue arises not in the alloy or the coating or the substrate, but if the substrate becomes exposed due to incomplete coverage, or a scratch through to the base metal because you then have a galvanic battery between two metals. Sengupta pop rivets an aluminum sheet to a stainless sheet with aluminum pop rivets it's not going to work :-)Įlectroplating and galvanizing and some other metal finishing processes also can alloy metals together in the same way. I think we're on different wavelengths, Jim: if Mr. Secondary zincate or chromate should help. This does not mean that there will be no breakdown of, say, the aluminum in a corrosive environment. There is no GALVANIC reaction because the metals behave as one. What am I missing? What material would you explosively bond onto the aluminum pop rivets?Įxplosion bonding creates a covalent (metallurgical) bond between the dissimilar metals. The explosive bonding sounds like a good method to bond dissimilar metals in some cases, Jim, but how does the fabrication method have any impact on galvanic corrosion? I thought it depended on factors (the emf difference between the two metals, a metallic connection, an ionic connection, and the relative surface areas) that have little to do with the connection method. Jim P Ĭonnector development - Wenatchee, Washington ![]() They make metallurgically bonded structures of dissimilar metals, specifically for sea coast environments where corrosion due to dissimilar metals in contact is a threat. High performance architectural metals - Cranberry Twp., PennsylvaniaĪ. ![]() In other words a relatively small anode area like an aluminum pop rivet will be attacked much faster than a large one like the 1/4" plate. The rate of galvanic corrosion is related directly to the ratio of cathode area (stainless) to anode area (aluminum). However, you may want to consider using stainless steel fasteners. Aluminum in a seacoast environment is not a long term proposition. Not ideal but good enough for government work. Epoxy paint the faying surfaces and pull the rivets wet (soaked, including inside) with zinc chromate primer. It must not adsorb any moisture however.Ī. You may be able to prevent it by putting an insulator between the two. Ted is correct, check out the EMF series, you'll see that aluminum is more active than the stainless (iron) so it will corrode preferentially. I think there's a 99 percent chance, Saibal, but maybe someone will offer encouragement.Ī. ![]()
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