Fretting wear of stainless steels under variable temperature conditions: Introduction of a 'composite' wear law

Fretting wear is perceived as a plague in many industrial fields (aeronautics, nuclear engineering, etc.). It is defined as a small displacement amplitude oscillatory motion between two contacting bodies. In this study, Jethete M152 steel was tested against A-286 steel under low pressure gross slip fretting conditions throughout a wide range of constant and variable temperatures from 23 degrees C to 400 degrees C. Friction and wear quantifications using a dissipated energy approach were carried out. Tests performed under constant temperature conditions show tribological discontinuities around 220 degrees C. Above this threshold temperature (T-t) a decrease of the friction coefficient and wear rate is observed, which is related to a significant modification of the interface. At lower temperatures severe adhesive wear dominates whereas at higher ones a third body abrasive process, involving the formation of a compliant glaze layer structure takes place. Various structural analyses including Raman spectroscopy confirm the hypothesis that the glaze layer structure is activated through a tribo-sintering process of oxidized wear particles. Besides. it is shown that the energy wear approach allows the wear kinetics to be determined. However, two different energy wear coefficients were identified depending on the temperature range. This confirms the idea that each wear mechanism is characterized by a specific wear rate. Variable temperature test conditions consisting of repeated sequences at 200 degrees C and 400 degrees C demonstrate a rather high reactivity of the interface regarding the evolution of the wear kinetics. Finally, a 'composite' wear law integrating the energy wear coefficient as a function of the temperature is introduced and its stability evaluated. (C) 2009 Elsevier B.V. All rights reserved.