Specific dissipated friction power distributions of machined carburized martensitic steel surfaces during running-in

Abstract

Due to new design specifications, current tribological systems are subjected to numerous modifications of their operating conditions such as lubrication regime, higher contact pressures, and longer operating times at lower maintenance costs. Thus the mixed lubrication regime might become most abundant. In order to still maintain ultra-mild sliding wear an approach is needed, which combines the contact conditions, surface topography, and near surface properties. One approach is to shorten the running-in phase e.g. by choosing well-aimed topographical parameters for optimized incipient contact conditions. In this study milled, ground, milled and finished, and polished samples were tested in a self-mating reciprocating ball-on-plane sliding wear tests while the tangential as well as the normal forces were measured simultaneously. After predefined test cycles 3D surface topographies as well as the wear rates were measured by means of confocal white light microscopy (CWLM). From all these data the specific dissipated friction power (SDFP), the contact temperatures are computed by means of a three dimensional elastic – ideal plastic contact model as well as the lubrication characteristics.This contribution shows the SDFP and relates it to the incipient topographies as well as their alterations during run-in. Considering the SDFP being distributed over the sliding domain the affected area (≈real contact area) can be evaluated as well. Now the SDFP can be related to the affected area and the marked differences of the running-in behavior even under ultra-mild sliding wear conditions become visible.