Developments in the oxidational theory of mild wear

Previous work in which the oxidational theory of the mild wear of metals has been applied to low alloy steels has revealed discrepancies between theoretical predictions and experimentally derived data. These were due to the incorrect assumption that oxidational constants measured under static conditions could be applied without change to the very different conditions which exist at the real areas of contact between two sliding surfaces. It is shown that although the activation energies (Q_p) for static and sliding conditions are likely to be the same, the accompanying Arrhenius constants (A_p) will be very different, leading to very different oxide growth rates.The authors have used previously reported friction, wear and heat flow results (for pin-on-disc wear experiments with a low alloy medium carbon steel) to obtain the best possible values of A_p (using published values of Q_p for static oxidation) consistent with an explanation of these results in terms of the oxidational theory of mild wear. These values of A_p and Q_p were then used to explain the wear behavior of a low alloy carbon steel when used in similar experiments. An essential feature of the successful correlation between theory and experiment was the analysis of the structure of the wear debris by X-ray diffraction, which enabled the appropriate values of Q_p and A_p to be assigned according to the interfacial temperatures indicated by these structures