Fatigue crack propagation behavior in railway steels

Fatigue crack propagation behavior in railway steels Purpose – The present paper aims to characterize the fatigue crack propagation behavior of wheel and rail steels, in particular the AVE wheel steel and an UIC60 rail steel, including several R ‐values and near threshold behavior. To accomplish this objective, mode I fatigue crack growth tests were performed according to the ASTM E647 standard on C(T) specimens taken from a Spanish high‐speed AVE train used wheel and a UIC60 rail, tested with 0.1, 0.4 and 0.7 load ratios. Design/methodology/approach – In the present study, the two different methodologies presented in the ASTM E647 standard were used to characterize the fatigue crack propagation behavior of the two studied materials. The K ‐decreasing test procedure was used to characterize fatigue crack propagation near the threshold, whereas the K ‐increasing with constant load range method was used in the Paris law regime. Findings – It was observed that for the wheel a small influence of R ‐ratio was found, with greater R implying higher fatigue crack growth rates. For the rail, the influence is small, and for large values of ΔK , it is slightly reversed. The near‐threshold results obtained indicate lower threshold values for higher R ‐ratio, a fact that is possibly associated with crack closure phenomena. A scanning electron microscope (SEM) study of fatigue crack propagation surfaces identified a random behavior in the striation orientation for both materials and no correlation was found between striation spacing and actual fatigue crack growth rate. Originality/value – R ‐ratio and threshold behavior of fatigue crack propagation of a steel used in high‐speed train wheels, as well as of UIC60 rail steel, were studied, with the objective of generating data to be used in maintenance and damage tolerance models. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png International Journal of Structural Integrity Emerald Publishing

Fatigue crack propagation behavior in railway steels

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Publisher
Emerald Publishing
Copyright
Copyright © 2013 Emerald Group Publishing Limited. All rights reserved.
ISSN
1757-9864
D.O.I.
10.1108/IJSI-10-2012-0029
Publisher site
See Article on Publisher Site

Abstract

Purpose – The present paper aims to characterize the fatigue crack propagation behavior of wheel and rail steels, in particular the AVE wheel steel and an UIC60 rail steel, including several R ‐values and near threshold behavior. To accomplish this objective, mode I fatigue crack growth tests were performed according to the ASTM E647 standard on C(T) specimens taken from a Spanish high‐speed AVE train used wheel and a UIC60 rail, tested with 0.1, 0.4 and 0.7 load ratios. Design/methodology/approach – In the present study, the two different methodologies presented in the ASTM E647 standard were used to characterize the fatigue crack propagation behavior of the two studied materials. The K ‐decreasing test procedure was used to characterize fatigue crack propagation near the threshold, whereas the K ‐increasing with constant load range method was used in the Paris law regime. Findings – It was observed that for the wheel a small influence of R ‐ratio was found, with greater R implying higher fatigue crack growth rates. For the rail, the influence is small, and for large values of ΔK , it is slightly reversed. The near‐threshold results obtained indicate lower threshold values for higher R ‐ratio, a fact that is possibly associated with crack closure phenomena. A scanning electron microscope (SEM) study of fatigue crack propagation surfaces identified a random behavior in the striation orientation for both materials and no correlation was found between striation spacing and actual fatigue crack growth rate. Originality/value – R ‐ratio and threshold behavior of fatigue crack propagation of a steel used in high‐speed train wheels, as well as of UIC60 rail steel, were studied, with the objective of generating data to be used in maintenance and damage tolerance models.

Journal

International Journal of Structural IntegrityEmerald Publishing

Published: Nov 14, 2013

Keywords: Threshold; Fatigue crack growth rates; Rail; Wheel

References

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