Fretting Corrosion
A wear process that occurs at the contact interface between tightly fitting metal surfaces subjected to micro-vibrations.
Fretting corrosion is a wear process that occurs at the contact interface between two tightly fitting metal surfaces that are subjected to micro-vibrations and sliding movements. These micro-oscillations wear away the protective oxide layer on the metal surface, exposing bare metal which rapidly oxidizes. The oxidized metal particles act as abrasive debris, accelerating wear in a destructive cycle.
In automotive components, fretting corrosion typically appears as a dark red or black powdery residue around joint interfaces. It is commonly found on splines, press-fit wheel bearings, bolt shafts, and electrical connector terminals (where it causes terminal fretting, leading to intermittent electrical connections). If left unchecked, it can lead to component binding, play, or fatigue cracking.
Symptoms of fretting corrosion include clicking noises from drive axles, electrical contact failures, and loose suspension joints. Mechanics prevent fretting by applying specialized lubricants, such as anti-seize or dielectric grease, to mating surfaces and electrical terminals, and ensuring fasteners are torqued to specification to prevent micro-movements. Once a press-fit journal has suffered fretting wear, it must be machined or replaced.