Definition - What does Galvanic Corrosion mean?
Galvanic Corrosion is a corrosive process that occurs when two different metals come in contact in an electrolytic solution or in certain circumstances that a corrosive reaction takes place. During the process, one grade of metal is active while the other grade is noble. The noble metal is protected and the more active metal tends to corrode in galvanic corrosion.
Petropedia explains Galvanic Corrosion
Metals and metal alloys possess different electrode potentials, a relative measure of a metal's tendency to become active in a given electrolyte. The more active or less noble a metal is, the more likely it will form an anode in an electrolytic environment. While the more noble a metal is, the more likely it will form a cathode when in the same environment. The electrolyte acts as a conduit for ion migration, moving metal ions from the anode to the cathode. The anode metal, as a result, corrodes more quickly than it otherwise would, while the cathode metal corrodes more slowly and, in some cases, may not corrode at all. For galvanic corrosion to occur, the metals should be electrochemically dissimilar, be in electrical contact, and they must be exposed to an electrolyte.