TY - JOUR
T1 - Rail degradation due to thermite weld discontinuities
T2 - Field experience
AU - Messaadi, Maha
AU - Grossoni, Ilaria
AU - Shackleton, Philip
AU - Shevtsov, Ivan
AU - Bezin, Yann
AU - Dollevoet, Rolf
PY - 2021
Y1 - 2021
N2 - 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.
AB - 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.
KW - Aluminothermic weld
KW - Dynamic load
KW - Geometrical discontinuity
KW - Metallurgical discontinuity
KW - Railhead ratchetting
UR - http://www.scopus.com/inward/record.url?scp=85112617764&partnerID=8YFLogxK
U2 - 10.1016/j.engfailanal.2021.105585
DO - 10.1016/j.engfailanal.2021.105585
M3 - Article
AN - SCOPUS:85112617764
SN - 1350-6307
VL - 128
JO - Engineering Failure Analysis
JF - Engineering Failure Analysis
M1 - 105585
ER -