Effect of geometric lath orientation on fatigue crack propagation via out-of-plane dislocation glide in martensitic steel

Shohei Ueki, Yoji Mine*, Xinyu Lu, Yu Lung Chiu, Paul Bowen, Kazuki Takashima

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Strain accumulation ahead of the fatigue crack tip in the martensite lath of a medium-carbon steel was examined using a three-dimensional electron backscatter diffraction (3D-EBSD) technique. The objective of this study is to explain the crack propagation mechanism due to the activation of out-of-plane slips with their Burgers vectors having no component of the crack growth direction, which exhibits high resistance to fatigue crack growth. The 3D-EBSD analysis revealed little misorientation in the crystal, concurrent with the fatigue crack propagation in the coarse laths oriented favourably for dislocation glide in their longitudinal directions. This suggests that these laths contributed to strain accommodation. In contrast, strain preferentially accumulated in the coarse laths oriented unfavorably for the longitudinal slip, promoting crack propagation. These indicate that the geometrical anisotropy and distribution of martensite laths dominate the fatigue crack propagation resistance in martensitic carbon steel.

Original languageEnglish
Article number114045
Number of pages6
JournalScripta Materialia
Early online date12 Jun 2021
Publication statusPublished - Oct 2021

Bibliographical note

Funding Information:
The authors are indebted to Mr. Yosuke Maeguchi, Kumamoto University, for his assistance in micro-mechanical tests. This work was supported in part by a Grant-in-Aid for Scientific Research (A) JP20H00311 and (B) JP19H02464 from the Japan Society for the Promotion of Science (JSPS). SU gratefully acknowledges the support of the ‘JSPS Overseas Challenge Program for Young Researchers’. This study used the plasma-FIB microscope at the centre for Electron Microscopy at the University of Birmingham, UK.

Publisher Copyright:
© 2021


  • Deformation structure
  • Fatigue
  • Martensitic steels
  • Micro-mechanical test
  • Slip

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering
  • Metals and Alloys


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