Plastic deformation below worn surfaces

Abstract

Large strains occur at and near the worn surface of a ductile material (e.g. ∼8 at a depth of 10 µm after trepanning, ∼2.5 at 2.5 µm below an abraded surface). The wear of such materials is thus controlled by their strain-hardening behavior. Measurements have been made of the strain and microhardness at points below the worn surface of copper-silver solder composite specimens. The results are consistent with a model of the abrasion process that suggests the strain below the surface should be proportional to the abrasive grit size and to the square root of the applied load, but the strain at the surface should be independent of these factors. A simple energy balance confirms the work done during wear is determined by the plastic deformation at and below the worn surface. The measured volume wear rate shows the linear dependence on load expected on the model of the abrasion process, but there is also some dependence on grit size at small grit sizes and possible reasons for this are discussed.