THE FRETTING BEHAVIOR OF ALSI7MG-T6

Investigations into the fretting behaviour of the AlSi7Mg-T6 aluminium alloy are presented in this paper. With regard to the surface finishi ng conditions of the material, two types of specimen were considered: (i) machined and (ii) machined and shot peened specimens. The research was focused on investigations into the influence of the number of cyc les, normal load (contact pressure) and the amplitude of slip on the f retting behaviour of the material. Fretting tests were performed under various running conditions with regard to normal load levels and slip amplitudes. The coefficient of friction between the surfaces at the f retting junction was continuously recorded. The fretting damage on che aluminium specimens was studied by means of microscopic and EPM analy ses. With regard to the evolution of coefficient of friction curves, t wo modes of fretting process were identified. They differ in the trans ition from the initial phase to the steady-state fretting regime and d epend primarily on the severity of the running conditions and the mate rial properties. In general, higher values of the coefficient of frict ion were observed with machined and shot peened specimens as compared with those which were machined. It was found that for a given normal l oad, the coefficient of friction increases with an increased amplitude of slip while, for a given amplitude of slip, it decreases with an in creased normal load. (C) 1997 Elsevier Science S.A.