on a technical engineering note, bonding dissimilar metals is an art. many of the newer USCG cutter classes (now getting a bit long in the tooth) started off with steel decks and hulls with aluminum superstuctures to save weight & add to stability. they were joined at the main deck with a lap joint with a synthetic rubber gasket, all bolted together. this made a perfect galvanic cell & the join rotted out very quickly. they discovered a trick to join them. explosive welding. they made a joint of steel on one side, aluminum on the other by exploding them together. the sides away from the joint could then be welded with normal steel and aluminum welding techiniques. the bond was so intimate it did not set up a galvanic cell.
japanese smiths have been hammer welding dissimilar metals in layers for artistic weapons fittings for centuries. the hammering taking the place of explosives.
