Amplitude-controlled transitions in fretting: the comparative behaviour of six materials

Abstract

Fretting tests have been carried out on six materials: EN3, EN56 and EN58 steels, copper, titanium and aluminium bronze. Each was tested at 1000 N normal load, for a total fretting distance of 2 km at peak-to-peak amplitudes of 6.5 and 65 μm. With the exception of the last material, the appearance of the fretted specimens differed at the two amplitudes and the difference in appearance was directly related to the amount of wear experienced. At the lower amplitude wear was always slight with very small, flat, smooth oxide beds, a few microscopic pits and very little material loss. At the higher amplitude wear tended to be far more severe with large amounts of pitting, surface roughening and the formation of more extensive, and generally looser, oxide debris. The results suggest that amplitude-based transitions in fretting behaviour appear to be real and widespread. Thus the phenomena associated with fretting are closely allied to the mechanics of the fretting process and are not purely material properties.