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Relating contact temperature and wear transitions in a wheel-rail contact
KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Tribologi.ORCID iD: 0000-0003-2489-0688
2011 (English)In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 271, no 1-2, 78-85 p.Article in journal (Refereed) Published
Abstract [en]

Earlier in an ongoing research project, we identified wear transitions, mechanisms, and regimes by experimentally testing the sliding part of a wheel-rail contact. Going further, the present study investigates the effects of elevated contact temperature and severe contact conditions corresponding to those of a wheel flange-gauge corner contact.

Prior studies discussed wear in terms of contact pressure, amount and type of lubricant, sliding velocity, generated airborne particles, wear depth, coefficient of friction, and topographical measurements. This study shifts the focus to contact temperature, elemental and morphological analysis of the airborne particles, and surface-layer microstructure of test specimens by using several analytical techniques (i.e., SEM, FIB, ESCA, and energy mapping).

As contact severity increased, the bulk temperature of the contacting bodies increased rapidly; this can be related to elevated contact temperature by judging the size and shape of the ultrafine particles generated. After test runs, the contacting bodies were analysed, revealing microstructural surface layer changes and differences in the amount of oxide formed in the immediate surface.

When the sliding part of the wheel-rail contact under severe contact conditions is experimentally simulated using pin-on-disc methodology, the discussion shifts from analyzing steady-state measurements, such as average wear rate, to more transient behaviours during running-in. Wear transitions occurring during running-in are decisive for the outcome of the rest of the test run, according to the present results.

Place, publisher, year, edition, pages
2011. Vol. 271, no 1-2, 78-85 p.
Keyword [en]
Wheel, Rail, Wear transition, Temperature, FIB, ESCA, SEM
National Category
Reliability and Maintenance
URN: urn:nbn:se:kth:diva-14164DOI: 10.1016/j.wear.2010.10.046ISI: 000291777600011ScopusID: 2-s2.0-79955765504OAI: diva2:331208
QC 20100721 8th Conference on Contact Mechanics and Wear of Rail/Wheel Systems (CM2009), Florence, ITALY, SEP, 2009Available from: 2010-07-21 Created: 2010-07-21 Last updated: 2011-12-15Bibliographically approved
In thesis
1. On wear transitions in the wheel-rail contact
Open this publication in new window or tab >>On wear transitions in the wheel-rail contact
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Wear transitions in the wheel–rail contact are of increasing interest since the general trend in railway traffic is toward increased velocities and axle loads. Curving increases the risk of flanging, causing the contact to change from an almost pure rolling wheel tread–rail head contact to more of a sliding wheel flange–rail gauge contact on the high rail in curves.

Under wheel flange–rail gauge contact conditions, wear transitions to severe or catastrophic wear will occur if the contact is improperly lubricated. Such a transition is the most undesirable transition in the wheel–rail contact, as it represents a very expensive operating condition for railway companies. The contact conditions responsible for this transition are very severe as regards sliding velocity and contact pressure, and thus place high demands on both the lubricant and the wheel and rail materials.

The focus of this thesis is on the transitions between different wear regimes in a wheel–rail contact. Wear is discussed both in traditional tribological terms and in terms of the categories used in the railway business, namely mild, severe and catastrophic wear. Most of the work was experimental and was performed at the Royal Institute of Technology (KTH), Department of Machine Design.

The effects of contact pressure, sliding velocity, and type of lubricant have been investigated, producing results that resemble those of other studies presented in the literature. The absence of research relating to the wheel flange–rail gauge contact is addressed, and it is concluded that a lubricant film must be present on rails in curves to prevent severe or catastrophic wear. The formulation of this lubricant can further increase its wear- and seizure-preventing properties. To obtain a deeper understanding of wear transitions, methods such as airborne particle measurement and electron microscopy have been used.

Paper A presents the test methodology used to detect seizure and discusses the wear-reducing influence of free carbon in highly loaded contacts.

Paper B presents the testing of seizure-initiating conditions for a range of environmentally adapted lubricants applied to wheel and rail materials; a transient pin-on-disc test methodology was used for the testing.

Paper C presents the use of pin-on-disc methodology to study the wear-reducing effects of a wide range of lubricants. The best performing lubricant was a mineral oil containing EP and AW additives.

Paper D relates wear rates and transitions to airborne particles generated by an experimentally simulated wheel–rail contact. The airborne particles generated varied in size distribution and amount with wear rate and mechanism.

Paper E relates additional analysis techniques, such as FIB sectioning, ESCA analysis, airborne particle measurements, and SEM imaging of airborne wear particles, to the contact temperature.


Place, publisher, year, edition, pages
Stockholm: KTH, 2009. 31 p.
Trita-MMK, ISSN 1400-1179 ; 2009:23
Wear transitions; Wheel; Rail; Wear regime; Wear mechanism
urn:nbn:se:kth:diva-11563 (URN)978-91-7415-511-2 (ISBN)
Public defence
2009-12-11, M3, Brinellvägen 64, KTH, Stockholm, 10:15 (Swedish)
Samba 6
QC 20100721Available from: 2009-11-20 Created: 2009-11-20 Last updated: 2012-01-27Bibliographically approved

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