Fretting corrosion is most likely to occur in which location?

• A. Fretting corrosion occurs in a location where there is a slight amount of relative movement between two components, and no way for the corrosive residue to be removed as it forms.
• B. On fully connected, stationary joints with no residue retention.
• C. Only on exterior surfaces away from joints.
• D. Where protective coatings are completely intact and residue is easily removed.

Answer: (A)

Fretting corrosion happens when two contacting parts experience tiny, repetitive movements that constantly rub away the protective films and wear debris is trapped at the contact site. This combination of movement and residue retention creates localized corrosion pits at the joint.

The described location fits perfectly: there’s a slight relative movement between components and no way for the corrosive residue to be removed as it forms, so wear, film disruption, and chemical attack all accumulate at that spot.

If the joints were fully connected and stationary with no residue retention, fretting wouldn’t occur because there’s no repeated rubbing or buildup at the contact surface. Exterior surfaces away from joints aren’t subject to this repetitive contact either, and intact protective coatings with easy residue removal would also minimize or prevent fretting.