An accelerated degree of corrosion occurring when two different metals are in contact with moisture, particularly sea water. All metals have what is termed a specific electric potential, so that low level electric current flows from one metal to another. A metal with a higher position in the galvanic series (see below) will corrode sacrificially rather than one with a lower position, meaning stainless, for example, will corrode before gold. The further apart the metals on the chart, the more electric current will flow and the more corrosion will occur. No serious galvanic action will occur by combining the same metals, only dissimilar ones. To prevent galvanic corrosion, use insulation, paint or coatings when separating dissimilar metals; or put the metal to be protected next to a metal which is not important in the assembly, so it can corrode sacrificially.
Metals listed first will corrode due to galvanic reaction before those at end of paragraph: magnesium, zinc, aluminum 1100, cadmium, aluminum 2024, steel and iron, lead, tin brass, copper, bronze, monel, 304 and 316 stainless (passive), silver, titanium, graphite gold.