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Study of Rolling Contact Fatigue Mechanism of ER9 and R260 Wheel/Rail Materials
Author(s)
Date Issued
October 24, 2024
Type
Conference Paper
Abstract
In railway operations, surface cracks due to rolling contact fatigue (RCF) are stress-induced defects that require further examination. The crack initiated at the wheel/rail interface propagates and thus leads to serious safety issues at the final fracture stage. This paper applies a cylinder-to-ball type of rolling contact fatigue rig to investigate the effect of contact pressure on rolling contact fatigue mechanisms and surface damage microstructure of ER9 wheel steel and R260 rail steel materials. Employing Hertzian contact theory, applied compressive forces used for different pressures were determined. The experiments were performed under dry conditions similar to most running trains. Results indicate that when the contact pressure increases, so does the severe surface damage. The service life of the materials decreases as stress increases. R260 rail material has a service life longer than ER9 wheel material at low contact pressure, but at contact pressures above 2.7 GPa, R260 rail material outperforms ER9 wheel material. Fractographic investigation demonstrates rolling contact fatigue damage evolution from flat surfaces to damaged surfaces in the form of flaking and spalling. Accelerometer measurements capture the damage mechanism stages from the crack nucleation stage of the test at acceleration amplitudes ranging from 0.5 to 0.75 times the force of gravity (G). A contact band appears on the specimen surfaces before the amplitude increases abruptly to about 1.0 G when surface cracks appear. Traces of surface cracking along the edge of the contact band cause stepwise acceleration jumps to 1.5 G, at which we ended the tests.
Citation
Aip Conference Proceedings, 3236(1), 2024