Dual-rotary Fretting Behavior of 7075 Aluminum Alloy

Base on a low-speed reciprocating rotary system, the combination of torsional fretting (TF) and rotational fretting (RF) under a contact of ball-on-flat was successfully realized by changing the title angle (α) of the shaft of rotary system. The dual rotary fretting (DRF) behavior of 7075 aluminum alloy against 52100 steel ball was investigated under tilt angles of 10°and 40° and varied angular displacement amplitudes. Dynamic analysis were performed in combination with microscopic examinations through optical microscopy, surface profilometer, scanning electric microscopy and energy dispersive analysis of X-ray. The results show that the running and damage behaviors of DRF of 7075 aluminum alloy were strongly dependent upon the tilt angle and angular displacement amplitude. With the increase of the title angle, the component of TF increased and the component of RF decreased accordingly. The mixed fretting regime and slip regime of DRF shifted to the direction of lower angular displacement amplitude with the increase of the asymmetry of damage morphology. Meanwhile, the wear mechanisms changed from delamination and oxidative wear to abrasive wear and oxidative wear.