Formation of Subsurface Zones in Impact Wear

Abstract

Recent studies have established that subsurface material structures are altered in processes giving rise to wear. This is the case both for sliding contact and repetitive compound impact loading. It is not surprising that the thermal and mechanical processing due to solid contact and relative motion lead to localized material property change. Yet subsurface material characteristics (such as degree of plastic deformation, void and crack content, layer formation, grain refinement, etc.) may be of considerable significance in terms of fundamental wear processes. Accordingly, a series of tests has been undertaken to determine the onset of characteristic subsurface zone formation arising in repetitive compound impact wear. The repetitive load cycling is convenient for such investigations (incubation studies) since a contact event is discretized a priori. The test series and subsequent analyses seek primarily to determine the dynamics of formation of subsurface material zones, and also to characterize these zones morphologically. The paper presents methodology and results from these studies.