Influence of displacement amplitude on fretting-induced friction and wear of steel in oil-lubricated contact

Many fretting-prone contacts are surrounded by oils, although they are not intended to lubricate them. To study the fretting behavior of contacts whose edge is exposed to engine oil, self-mated 34CrNiMo6+QT steel was employed with a large annular flat-on-flat contact. A displacement-controlled loading was tested in a range, encompassing stick and gross sliding. No stick-to-slip transition with displacement amplitude was observed up to a tangential-to-normal traction ratio of 1.6, compared to that of 0.5 in dry contact. Beyond that, a typical peak-to-stabilized friction curve was reached in oil with a steady-state value of roughly 0.4, lower than that of dry contact. Adhesive wear existed as the dominant wear mechanism, and the severity of adhesion increased with higher loading.