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説明:

This study aimed to identify the microstructural factors governing the torsional fatigue strength of bainitic steels. Torsional fatigue tests were performed on two bainitic steels with banded microstructures comprised of soft and hard layers. The soft layers were coarse-grained with low Vickers hardness (HV), while the hard layers were fine-grained with high HV. Both materials possessed similar average HV values but differing band morphologies: a coarse band (CB) with HV = 329 and a fine band (FB) with HV = 314. Interestingly, the FB exhibited a 30 % higher fatigue strength than the CB. Through microscopic observations and finite element analysis, it was established that different fatigue strengths could be attributed to the particular width and array of the bands. The reticular band array in the FB steel raises crack initiation resistance due to the constraint of cyclic plastic deformation. In addition, the narrower spacing of hard layers can impede crack propagation when the extension mode transitions from shear mode to Mode I. In contrast, the columnar array and wider spacing of the bands in the CB steel are likely to provide weaker resistance to crack initiation and propagation, resulting in an inferior fatigue strength.

権利情報:

• Creative Commons BY-NC-ND Attribution-NonCommercial-NoDerivs 4.0 International
  

キーワード: Bainitic steel, Banded microstructure, Torsional fatigue strength, Small crack, Finite element analysis

刊行年月日: 2024-11-17

出版者: Elsevier BV

掲載誌:

• International Journal of Fatigue (ISSN: 01421123) vol. 192 108714

研究助成金:

原稿種別: 出版者版 (Version of record)

MDR DOI:

公開URL: https://doi.org/10.1016/j.ijfatigue.2024.108714

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更新時刻: 2024-12-24 13:58:16 +0900

MDRでの公開時刻: 2024-12-24 13:58:16 +0900