An Investigation of the Fretting Corrosion of Closely Fitting Surfaces

Abstract

The paper describes an experimental investigation of the mutual corrosion of metal surfaces in closely fitting contact when subject to vibration. It is shown that the corrosion is mechanical rather than chemical in character. Vibration or alternating surface stress alone will cause no corrosion and it is established that some surface slip, alternating in direction, is the necessary condition. Slip effectively causes corrosion even if reduced to the order of molecular dimensions, and this has been found to occur without exception, whatever the condition of the surfaces. Lubricants modify but do not prevent corrosion. Softer materials in general tend to seize and harder materials to produce corrosion debris. The amount of corrosion does not appear to depend on the intensity of normal pressure, but only on the occurrence of contact. Comparative tests of many pairs of materials show differences in the resistance offered to corrosion, but no pair of materials has been found to be free from the effect. A theoretical discussion of the mechanism of the phenomenon is given in which the idea of ordinary mechanical abrasion is rejected, and a process of molecular attrition, possibly closely associated with fatigue effect, is suggested.