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Interior crack initiation during the very-high-cycle fatigue of railway wheel steel under axial loading and rolling contact loading
  • +2
  • Xiao-Long Liu,
  • Pengcheng Gao,
  • Si Wu,
  • Guanzhen Zhang,
  • Tao Cong
Xiao-Long Liu
Beijing Jiaotong University School of Electronic and Information Engineering

Corresponding Author:liuxiaolong@bjtu.edu.cn

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Pengcheng Gao
Beijing Jiaotong University School of Electronic and Information Engineering
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Si Wu
China Academy of Railway Sciences Corporation Limited
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Guanzhen Zhang
China Academy of Railway Sciences Corporation Limited
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Tao Cong
China Academy of Railway Sciences Corporation Limited
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Abstract

In this paper, a comparative study of the very-high-cycle fatigue (VHCF) behavior of railway wheel steel under axial loading and rolling contact loading was conducted. Fatigue tests were performed with an ultrasonic fatigue test machine under axial loading, and the fracture surfaces from the fatigue tests and shattered rims taken from the failed railway wheels were observed. The wheel steel under axial loading presents a VHCF behavior with Mode I crack, and that under rolling contact loading is a VHCF behavior with mix Mode II-III crack. For the VHCF behavior with Mode I crack ,surface and interior crack initiation occurred with equal probability at both low and high stress levels and produced a dual linear S-N curve since the value of fatigue limits for the surface and interior crack initiation are close. For the VHCF behavior with mix Mode II-III crack, cracks were initiated from the interior Al 2O 3 inclusion and the fatigue life was beyond 10 7 cycles. Fatigue bands were observed on the fracture surface under rolling contact loading. The ferrite nanograins formed due to the stress state of shear plastic strain with a large compressive stress. The formed nanograins were softer than the matrix caused by the redistribution of the carbon.
Jul 2022Published in Fatigue & Fracture of Engineering Materials & Structures volume 45 issue 7 on pages 2127-2138. 10.1111/ffe.13724