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Keywords: early-damaging, rolling contact fatigue, laboratory-scale testing, tribology, wear.

Summary

The aim of the study described in this paper was the experimental modeling of a cyclic wheel/rail contact at laboratory-scale to investigate wear behaviour and rolling contact fatigue. A novel testing system was established using a transverse oscillating movement to reproduce the unidirectional loading on a rail track. Compared with other laboratory-scale test methods (e.g. twin-disc testing) tribotests are performed with real rail parts. The tests were done on the gauge corner of the rail in order to reach similar contact stresses as in the real system. The counterpart was a model wheel at an adjusted contour to the rail section. Rails with different hardness, heat treatment and surface pre-conditioning were investigated. For determination of crack initiation and crack growth rate, the wear rate and the number of loading cycles were varied. Wear was measured using three dimensional confocal microscopy in order to detect volume loss and changes in surface topography. Quantitative crack analysis was undertaken for the longitudinal micro-section of the contact zone using optical microscopy. The experimental simulation of the wheel/rail-contact was able to reproduce "head checks", regular cracks on the gauge corner of the rail. The results showed that the distance between the surface microcracks and the size of the micro-cracks decreases with increasing hardness of the rail. Rail surface condition influenced micro-crack initiation, since milled rail surfaces without decarburized near-surface zones exhibited crack initiation after higher testing cycles compared with an as-rolled surface condition where microcrack initiation and growth was shifted to an earlier stage in the testing. The literature implies that for low wear rates rolling contact fatigue might become an important failure mechanism are at least qualitatively validated by this tribometrical approach.

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Front Page Browse CCP CSETS CTR IJRT Other Authors Search Purchase Guide FAQ Contact us	Civil-Comp Proceedings ISSN 1759-3433 CCP: 104 PROCEEDINGS OF THE SECOND INTERNATIONAL CONFERENCE ON RAILWAY TECHNOLOGY: RESEARCH, DEVELOPMENT AND MAINTENANCE Edited by: J. Pombo Paper 188 Influence of Heat Treatment and Surface Condition on Early-Damaging of Rail Materials A. Trausmuth¹, T. Lebersorger¹, E. Badisch¹, S. Scheriau² and H.P. Brantner² ¹Austrian Center of Competence for Tribology, AC²T research GmbH, Wiener Neustadt, Austria ²Voestalpine Schienen GmbH, Leoben, Austria doi:10.4203/ccp.104.188 purchase the full-text of this paper Full Bibliographic Reference for this paper A. Trausmuth, T. Lebersorger, E. Badisch, S. Scheriau, H.P. Brantner, "Influence of Heat Treatment and Surface Condition on Early-Damaging of Rail Materials", in J. Pombo, (Editor), "Proceedings of the Second International Conference on Railway Technology: Research, Development and Maintenance", Civil-Comp Press, Stirlingshire, UK, Paper 188, 2014. doi:10.4203/ccp.104.188 Keywords: early-damaging, rolling contact fatigue, laboratory-scale testing, tribology, wear. Summary The aim of the study described in this paper was the experimental modeling of a cyclic wheel/rail contact at laboratory-scale to investigate wear behaviour and rolling contact fatigue. A novel testing system was established using a transverse oscillating movement to reproduce the unidirectional loading on a rail track. Compared with other laboratory-scale test methods (e.g. twin-disc testing) tribotests are performed with real rail parts. The tests were done on the gauge corner of the rail in order to reach similar contact stresses as in the real system. The counterpart was a model wheel at an adjusted contour to the rail section. Rails with different hardness, heat treatment and surface pre-conditioning were investigated. For determination of crack initiation and crack growth rate, the wear rate and the number of loading cycles were varied. Wear was measured using three dimensional confocal microscopy in order to detect volume loss and changes in surface topography. Quantitative crack analysis was undertaken for the longitudinal micro-section of the contact zone using optical microscopy. The experimental simulation of the wheel/rail-contact was able to reproduce "head checks", regular cracks on the gauge corner of the rail. The results showed that the distance between the surface microcracks and the size of the micro-cracks decreases with increasing hardness of the rail. Rail surface condition influenced micro-crack initiation, since milled rail surfaces without decarburized near-surface zones exhibited crack initiation after higher testing cycles compared with an as-rolled surface condition where microcrack initiation and growth was shifted to an earlier stage in the testing. The literature implies that for low wear rates rolling contact fatigue might become an important failure mechanism are at least qualitatively validated by this tribometrical approach. purchase the full-text of this paper (price £20) go to the previous paper go to the next paper return to the table of contents return to the book description purchase this book (price £65 +P&P)
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