Abrasive wear (three-body)

Abrasive wear occurs when a harder material slides or rubs against a softer material that cuts into or abrades the softer material away. Three-body abrasive wear occurs when a hard contaminant (such as a particle of grit or wear debris) becomes entrapped between two mating faces, and embeds into a soft surface. As the parts move the hard particle cuts, pows, or gouges the opposing surface leaving score lines in the direction of motion.

Diagram of abrasive three-body wear