Shear-mode Crack Initiation Behavior in the Martensitic and Bainitic Microstructures

Kentaro Wada, Soma Yoshimura, Tomoko Yamamoto, Yoshihiro Ohkomori, Hisao Matsunaga

研究成果: Contribution to journalConference article査読


Fully reversed torsional fatigue tests were conducted to elucidate the behaviour of shear-mode crack initiation and propagation in one martensitic and two bainitic steels. The relationship between the crack initiation site and microstructure was investigated by means of an electron backscatter diffraction (EBSD) technique. From the S-N diagram, two notable results were obtained: (i) the shear-mode crack was initiated on the prior austenitic grain boundary in martensitic steel, while in bainitic steels, the crack was initiated along the {110} plane; one of the slip planes of bcc metals, and (ii) the torsional fatigue limit of lower bainitic steel with finer grains was 60 MPa higher than that of upper bainitic steel with coarser grains even though the hardnesses were nearly equivalent. The mechanism determining the torsional fatigue strength in these steels is discussed from the viewpoint of microstructure morphology.

ジャーナルMATEC Web of Conferences
出版ステータス出版済み - 5 25 2018
イベント12th International Fatigue Congress, FATIGUE 2018 - Poitiers Futuroscope, フランス
継続期間: 5 27 20186 1 2018

All Science Journal Classification (ASJC) codes

  • 化学 (全般)
  • 材料科学(全般)
  • 工学(全般)


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