Which metal is most susceptible to galvanic corrosion?

Galvanic corrosion occurs when two different metals are in electrical contact in the presence of an electrolyte, leading to accelerated corrosion of the more anodic (less noble) metal. Iron is considered one of the most susceptible to galvanic corrosion because it has a relatively low position in the galvanic series, making it more anodic compared to many other metals. When iron is in contact with metals that are more cathodic, such as copper or aluminum, the iron will corrode preferentially due to the electrochemical processes occurring at the anode and cathode.

In contrast, metals such as gold and lead are more noble and thus are much less prone to corrosion in galvanic cell scenarios. Gold, being highly resistant to electrochemical reactions, tends to remain unaffected even when placed in contact with more reactive metals. Aluminum, while it can corrode, forms a protective oxide layer that provides some barrier against further corrosion, making it less susceptible than iron under similar conditions. Therefore, iron's positioning in the galvanic series and its susceptibility to environmental factors contribute significantly to its vulnerability to galvanic corrosion.