Scuffing Under Dry Sliding Conditions—Part I: Experimental Studies

Abstract

The scuffing behavior of four materials sliding against 1018 carburiud steel is experimentally studied under dry sliding conditions. These materials are commercially pure aluminum (1100), die-cast hypereutectic aluminum-silicon alloy (390-T6), extruded Bi-containing eutectic aluminum-silicon alloy (DHT-3), and 1018 steel. The major emphasis is on the 390-T6 aluminum alloy. The environment for the tests is either air or tetrafluoroethane (R134a). The effects of load, sliding velocity, mechanical strength, environmental temperature, specimen size, time, loading history, and type of environment are evaluated. The mechanisms leading to scuffing are studied by examination of surfaces, subsurfaces and wear debris of specimens in the process of scuffing. Quantitative measurements of subsurface plastic deformation are also obtained. Based on the experimental observations it is concluded that scuffing is due to a subsurface material failure. This process involves initiation of cracks due to subsurface plastic deformation, propagation of these cracks leading to the removal of the existing protective surface layers and, finally, cold welding due to adhesion between bare metal surfaces.