Study on bending fretting fatigue damages of 7075 aluminum alloy

Bending fretting fatigue tests of 7075 aluminum alloy cylinders against 52100 steel cylinders orthogonally have been carried out under a same normal load and varied bending loads. The S–N curve of the bending fretting fatigue showed a characteristic of “C curve”. Based on the OM, SEM, and TEM, the fretting fatigue damages of 7075 alloy have been analyzed in detail. A physical model was set up to describe the surface damage and the crack formation process in MFR. The TEM analyses showed that the stress concentration at the wall of dislocation cells was the reason of the fatigue crack initiation.

► The S–N curve of the 7075 aluminum alloy was built up.
► The bending fretting fatigue cracks initiated in the subsurface.
► A physical model was set up to describe the damage in the mixed fretting regime.
► Abrasive wear, oxidative wear and delamination were the main damage mechanisms.