What are pits and how are they caused?

Pits are small, localized areas of corrosion that result in the formation of cavities or hollow spots on the surface of a material, typically metals. This phenomenon is largely caused by oxidation, where an electrolyte, such as moisture, allows for the continuous process of corrosion to occur. Pitting corrosion is often influenced by factors like the presence of chloride ions, localized corrosion in aggressive environments, and can occur in stainless steels or other alloys when they are exposed to specific conditions.

Understanding the nature of pits as small hollow spots due to oxidation clarifies the mechanisms at play, including how materials can selectively corrode at particular areas, often due to microstructural differences or protective oxide layers breaking down. This differentiation helps in the control and prevention of corrosion through methods like coating, material selection, and environmental modifications.