Metallography of adhesive wear in aluminum alloys

The wear characteristics of two aluminum alloys, 1100 and 3004, were studied using a pin-on-disc wear test with a normal load of 1 kg and a sliding velocity of 0.25 m/s. Measurements were made of the coefficient of friction and wear rate for unlubricated contact between the alloys and a spherical tungsten carbide slider. A two-surface metallographic technique was developed for simultaneous observation of the wear surface topography and the microstructure of the polished section perpendicular to this surface.The observations indicate the following: 1.1. Large local strains and strain gradients are present adjacent to the wear surface.2.2. Second-phase particles provide nucleation sites for surface cracks and decohesion of material from the surface.3.3. Adhesive wear appears to involve a process of cumulative damage due to void growth in the stress field beneath the sliding indenter.