• Ferreira, La
• Peixoto, D.

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 DK, 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. © Emerald Group Publishing Limited.

Topics

• impedance spectroscopy
• surface
• scanning electron microscopy
• crack
• steel
• fatigue
• random