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Keywords: wheel and rail materials hardness effects on wear, wear rates, work hardening, wear mechanisms.

Summary

In this paper, a review is presented on investigations of how the wear of wheel and rail material changes when the hardness of the opposing pair is varied. Tests across all scales in the laboratory and in the field have shown similar trends and follow the model, proposed by Steele & Reiff in 1982, based on the rail to wheel hardness ratio. This states that where the rail is softer than the wheel, rail wear decreases with increasing rail hardness, and wheel wear increases. Where the rail is harder than the wheel, again rail wear decreases with increasing rail hardness, but wheel wear remains constant. In both cases, however, as rail hardness increases overall system wear reduces. This information will help allay fears held by some railway managers and practitioners that introduction of premium rail or wheel materials will have a detrimental effect on the opposing material.

While the wear trends appear well characterised some issues have been identified. One relates to the varying work hardening capability of wheel and rail materials. Often only bulk hardness is quoted, but work hardening can increase material surface hardness by up to 2.5 times and make materials that were initially softer, harder than the opposing material. Another related issue is test length. It is essential that enough cycles are applied such that the materials reach steady state wear, i.e., the point at which work hardening has reached its limit. In previous work it is not always clear that steady state wear has been reached. Some gaps have been identified in the current knowledge base, the largest of which is the failure to determine which mechanisms lead to the wear trends seen. The analysis of the work hardening of the wheel material in particular, may be a large help in this regard. Work is ongoing to expand data in this area.

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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: 110 PROCEEDINGS OF THE THIRD INTERNATIONAL CONFERENCE ON RAILWAY TECHNOLOGY: RESEARCH, DEVELOPMENT AND MAINTENANCE Edited by: J. Pombo Paper 151 Investigation of the Influence of Rail Hardness on the Wear of Rail and Wheel Materials under Dry Conditions R. Lewis¹, W.J. Wang², M. Burstow³ and S.R. Lewis¹ ¹Department of Mechanical Engineering, The University of Sheffield, United Kingdom ²Tribology Research Institute, Southwest Jiaotong University, Chengdu China ³Network Rail, Milton Keynes, United Kingdom doi:10.4203/ccp.110.151 purchase the full-text of this paper Full Bibliographic Reference for this paper R. Lewis, W.J. Wang, M. Burstow, S.R. Lewis, "Investigation of the Influence of Rail Hardness on the Wear of Rail and Wheel Materials under Dry Conditions", in J. Pombo, (Editor), "Proceedings of the Third International Conference on Railway Technology: Research, Development and Maintenance", Civil-Comp Press, Stirlingshire, UK, Paper 151, 2016. doi:10.4203/ccp.110.151 Keywords: wheel and rail materials hardness effects on wear, wear rates, work hardening, wear mechanisms. Summary In this paper, a review is presented on investigations of how the wear of wheel and rail material changes when the hardness of the opposing pair is varied. Tests across all scales in the laboratory and in the field have shown similar trends and follow the model, proposed by Steele & Reiff in 1982, based on the rail to wheel hardness ratio. This states that where the rail is softer than the wheel, rail wear decreases with increasing rail hardness, and wheel wear increases. Where the rail is harder than the wheel, again rail wear decreases with increasing rail hardness, but wheel wear remains constant. In both cases, however, as rail hardness increases overall system wear reduces. This information will help allay fears held by some railway managers and practitioners that introduction of premium rail or wheel materials will have a detrimental effect on the opposing material. While the wear trends appear well characterised some issues have been identified. One relates to the varying work hardening capability of wheel and rail materials. Often only bulk hardness is quoted, but work hardening can increase material surface hardness by up to 2.5 times and make materials that were initially softer, harder than the opposing material. Another related issue is test length. It is essential that enough cycles are applied such that the materials reach steady state wear, i.e., the point at which work hardening has reached its limit. In previous work it is not always clear that steady state wear has been reached. Some gaps have been identified in the current knowledge base, the largest of which is the failure to determine which mechanisms lead to the wear trends seen. The analysis of the work hardening of the wheel material in particular, may be a large help in this regard. Work is ongoing to expand data in this area. purchase the full-text of this paper (price £22) 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 £85 +P&P)
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