EA4T railway axle steel fatigue behavior under very high-frequency fatigue loading. (September 2020)

• Record Type: Journal Article
• Authors: Fintová, Stanislava; Pokorný, Pavel; Fajkoš, Rostislav; Hutař, Pavel
• Is Part Of: Engineering failure analysis. Volume 115(2020)
• Publication Date: 2020-09
• Subjects: EA4T -- Fatigue -- 20 kHz -- Non-inclusion fatigue crack initiation; System failures (Engineering) -- Periodicals; Fracture mechanics -- Periodicals; Reliability (Engineering) -- Periodicals; Pannes -- Périodiques; Rupture, Mécanique de la -- Périodiques; Fiabilité -- Périodiques; Fracture mechanics; Reliability (Engineering); System failures (Engineering); Periodicals; Electronic journals; 620.112
• DOI: 10.1016/j.engfailanal.2020.104668
• Languages: English
• ISSNs: 1350-6307

Abstract

Highlights: S-N curve shift was observed increasing the testing frequency from 120 Hz to 20 kHz. The same fatigue endurance limit was determined for 20 kHz and for 120 Hz. Surface and subsurface crack initiation was responsible for specimens failure. No slip markings were observed on the polished specimens gauge lengths. Abstract: One of the most loaded components of the train, with very long operation time, is a railway axle. During its operation, the conventional fatigue limit of 10 7 cycles is reached easily and information about fatigue behavior for a higher number of cycles is missing. Therefore, the fatigue behavior of railway axle EA4T heat-treated steel with a bainitic microstructure was examined under very high-frequency fatigue loading. S-N curve shift to the higher number of cycles at the same stress amplitude due to the testing frequency increase was observed. However, the same fatigue endurance limit of 375 MPa was determined for 10 7 cycles at a frequency of 120 Hz and for 10 10 cycles at a frequency of 20 kHz. Due to homogenous and fine bainitic structure in a whole tested volume of material, the same fatigue crack initiation and propagation mechanism was observed to be characteristic for all the tested specimens, regardless of the used testing frequency and stress amplitude. Surface and subsurface non-inclusion fatigue crack initiation was responsible for the failure of the specimens. Obtain results confirm, that fatigue endurance limit determined by traditional high fatigue test can be used also for several orders higher number of cycles.