The role of the thermal conductivity of steel in quantitative elastohydrodynamic friction

Numerical models for thermal elastohydrodynamic lubricated contacts of steel surfaces have always employed a value for the thermal conductivity of steel corresponding to its soft annealed alloy state. However, steel in elastohydrodynamic lubricated contacts is usually hardened. It has been known for...

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Veröffentlicht in:Tribology international 2020-02, Vol.142, p.105970, Article 105970
Hauptverfasser: Habchi, Wassim, Bair, Scott
Format: Artikel
Sprache:eng
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Zusammenfassung:Numerical models for thermal elastohydrodynamic lubricated contacts of steel surfaces have always employed a value for the thermal conductivity of steel corresponding to its soft annealed alloy state. However, steel in elastohydrodynamic lubricated contacts is usually hardened. It has been known for more than a century now (not within the Tribology community though) that the thermal conductivity of steel could be reduced by a factor of more than two when it is hardened. Only recently did the Tribology community realize this “mistake”, of which the impact on friction predictions is investigated in this work. The mistake is found to lead to significant overestimations of friction in the thermo-viscous regime. •TEHL simulations of steel contacts have always used the thermal conductivity of soft steel.•Steel in EHL contacts of test rigs or real-life machine elements is usually hardened.•Hardened steel has a much lower thermal conductivity than soft annealed steel.•Using the wrong value of soft steel thermal conductivity leads to an overestimation of friction.•Friction prediction errors are linked to lubricant film and bounding solids' temperature variations.
ISSN:0301-679X
1879-2464
DOI:10.1016/j.triboint.2019.105970