LUBRICATED FRETTING WEAR OF A HIGH-STRENGTH EUTECTOID STEEL ROPE WIRE

The fretting wear behaviour of heavily work-hardened eutectoid steel wire is an important issue in the construction and usage of locked coil steel ropes. These ropes, which are used for high duty applications in aggressive environments, such as those encountered in the mining industries, can exhibit a variable service life. Earlier papers examined the design features of this class of rope and aspects of the operating regime, which may contribute to this variable life. The as-drawn surface of the wire was determined to play a significant role in the fretting behaviour, initially suppressing wear and friction. In this paper, the influence of low viscosity oils, with and without graphite additions, on the fretting behaviour of the as-drawn wire are examined. Oil bath lubrication suppresses effectively wear and friction throughout the tests. Of greater significance, however, a smear of oil, more typical of service conditions, is also effective, at least during the early stages of testing. The addition of graphite to this smear of oil aids its retention, and its ability to lubricate and form a shield around the fretting interface. The presence of oil inhibits the ingress of oxygen and consequently, at higher normal forces, when significant breakdown of the oil film occurs, micro-welding and tearing of the clean metal surfaces follows. Even so, wear and friction are still suppressed effectively.