Plastic deformation and sliding friction of metals

Most theories of sliding friction have emphasized surface roughness or adhesion. In some cases plastic deformation has been invoked to account for energy dissipation. After a brief review of published explanations of friction, a new model is described for the source of friction during the steady state sliding of metals. It focuses on the plastic work done in the near-surface region, described in terms of work hardening, recovery and the microstructure existing during steady state sliding. The model is discussed with respect to several alternate ways in which plastic deformation has been incorporated in recent theories of friction. Reasonable results are found when the new model is used to estimate friction coefficients for metals. Also, the model appears to be consistent with a number of published observations on the relation of friction to load, sliding distance, surface temperature and microstructure, and with a model for sliding wear which has been presented earlier.