Surface topography and integrity effects on sliding wear

The effect of surface roughness and integrity on the sliding wear of metals was investigated experimentally. The results are consistent with the delamination theory of wear. The initial wear rate was influenced by the surface roughness and the applied load but the steady state wear rate was independent of the initial roughness. Under low applied loads delamination of smooth surfaces commences soon after sliding is initiated, whereas the delamination of rough surfaces is delayed until the original asperities are worn. Consequently, under low loads the initial wear rate of a smooth surface is higher than that of a rougher surface. The opposite is found under high loads since original asperities are removed immediately. It is also shown that machining damage to the surface or the subsurface (in the form of deformation, voids and cracks) accelerates the initial wear rate of the machined surface.