Fretting corrosion is most likely to occur due to what condition?

• A. Repetitive micro-motions between contacting surfaces
• B. High ambient temperature
• C. Absence of lubrication
• D. Immersion in water

Answer: (A)

Fretting corrosion occurs when two surfaces that are in contact under load experience small, repetitive sliding at the contact patch. Those micro-motions continually shear and wear away the protective oxide film, exposing fresh metal to the surrounding environment. The cycle of oxide removal and reformation under these tiny oscillations accelerates localized corrosion right at the contact area. Lubrication helps reduce this wear by preventing metal-to-metal contact, while temperature or immersion in water can speed up corrosion in general but don’t define the fretting mechanism itself. Absence of lubrication alone isn’t enough to cause fretting; it’s the repeated micro-motions between the surfaces under load that drive it.