Rail degradation due to thermite weld discontinuities: Field experience

Maha Messaadi, Ilaria Grossoni, Philip Shackleton, Ivan Shevtsov, Yann Bezin, Rolf Dollevoet

Research output: Contribution to journalArticleScientificpeer-review

Abstract

This paper details the field-testing approach and results of thermite welds used in railway applications. Rail steels made from R260 grades are welded by two different processes: the standard process according to the European standards, and a recent technology. Welds are introduced in the same testing location to ensure comparable loading conditions in the aim of studying their degradation behaviours. The total testing-period is 6 months. During the in-service period, the surface hardness of the running band, in the welded area, is recurrently measured. For an accurate assessment of field results, a vehicle/track interaction (VTI) model evaluated the expected dynamic loads induced by the initial vertical irregularities. The simulations show that the highest dynamic load at the wheel/rail contact happens at the location of the maximum absolute gradient, in accordance with previous research. Particularly, dipped welds show relatively high dynamic forces inducing a high loss of the transversal profile. In respect of the field results, the comparison of initial and final surface hardness indicates a significant increase for ‘ALFONS’ welds over the welded areas. Additionally, all welds depicted a cyclic increase and decrease of the running band hardness. This result is discussed according to the ratcheting susceptibility of welds and eventual wear progression. For a testing-period of 10 weeks, the gauge corner of one ‘ALFONS’ weld developed a crack. The assessment of the longitudinal profiles revealed changes of the vertical irregularities that may modify the dynamic loads, and further the rolling contact fatigue mechanisms and degradation rates.

Original languageEnglish
Article number105585
Number of pages14
JournalEngineering Failure Analysis
Volume128
DOIs
Publication statusPublished - 2021

Keywords

  • Aluminothermic weld
  • Dynamic load
  • Geometrical discontinuity
  • Metallurgical discontinuity
  • Railhead ratchetting

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