Fretting

Fretting (or fretting corrosion) refers to corrosion damage at the asperities of contact surfaces. This damage is induced under load and in the presence of repeated relative surface motion, as induced for example by vibration. The ASM Handbook on Fatigue and Fracture defines fretting as: "A special wear process that occurs at the contact area between two materials under load and subject to minute relative motion by vibration or some other force."

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Some examples include the pitting of bicycle headset bearings due to fork flexing, wear of bicycle cranks caused by precession of the harder steel pedal spindle, and car wheel bearings becoming pitted due to the rocking motion they experience when new cars are transported by railway.

There is a current focus on fretting research in the aerospace industry. The dovetail blade-root connection and the spline coupling of gas turbine aerogines experience fretting during their service life.

Fretting damage is identified by the presence of rouge (iron oxide powder) and the rough, torn appearance of the pitted surface.

See also

• Tribology