An investigation of the roles of crack initiation, propagation and ratchetting in producing wear in metallic sliding contacts

Experiments are described in which the edge of a hard wedge is loaded against the periphery of a rotating disc of softer specimen material. The normal and frictional forces and inward movement of the wedge as the disc wears are continually monitored throughout a test. The results obtained are used together with measurements of the wearing surfaces of metallographic sections to test a newly proposed wear model. In this model it is assumed that ratchetting causes failure of the surface and hence the production of wear particles, while low-cycle fatigue determines the crack propagation rate and hence the wear rate.