What is galvanic corrosion?

Galvanic corrosion occurs specifically when two different types of metals are in direct contact with each other while both are immersed in an electrolyte, which could be water containing salts or other ions that facilitate electrical conductivity. This particular type of corrosion happens due to the electrochemical reaction between the dissimilar metals, leading to the more anodic metal corroding faster than it normally would in the absence of the other metal.

The presence of an electrolyte allows for the flow of electric current between the metals, exacerbating the corrosion process. This phenomenon is of concern in marine environments where metals like aluminum and steel may come into contact and lead to accelerated wear and deterioration.

Other options miss the mark because they either describe different forms or conditions of corrosion that are not specifically linked to the interactions of dissimilar metals. For instance, corrosion caused by rainwater pertains to environmental exposure rather than a galvanic reaction, high-temperature corrosion involves different mechanisms, and the notion that corrosion only occurs in freshwater disregards the broad variety of environments, including saltwater, which is particularly relevant in naval applications.