What type of corrosion occurs in metal-to-metal joints such as riveted joints where skins overlap?

The correct answer is concentration cell corrosion. This type of corrosion arises in situations where there is a difference in the concentration of an electrolyte, typically due to the presence of trapped moisture or contaminants in the overlapping areas of riveted joints. In these scenarios, areas with different concentrations can create electrochemical cells, leading to localized corrosion at points where the metal-to-metal contact occurs.

In riveted joints, where two metal surfaces overlap, it is essential to understand that water and other electrolytes can accumulate in the joint. This moisture retention, combined with variations in the exposure conditions of the metals, can lead to the establishment of concentration cells. One area might have a higher concentration of dissolved oxygen or ions compared to another area, resulting in the corrosion of the more anodic metal.

Pitting corrosion generally refers to localized corrosion that results in small pits or holes forming on the metal surface and is driven primarily by other factors such as exposure to aggressive environments. Creeping corrosion, while it may involve movement along a surface, does not specifically describe the phenomena occurring in overlapping joints as concentration cell corrosion does. Intergranular corrosion targets the grain boundaries of metals, which is a different process not directly related to the conditions present in riveted or overlapping joints. Understanding these distinctions