Optical microscopy-Based damage quantification: an example of cryogenic deformation of a dual-Phase steel

Nao Uehata, Motomichi Koyama, Shusaku Takagi, Kaneaki Tsuzaki

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)


We evaluated the availability of an optical-microscopy-based damage quantification method in a ferrite/ martensite dual-phase steel, and interpreted the obtained results toward screening damage evolution behavior under various test conditions. In this study, we employed this method for tensile deformation at 20, −100, and −180°C to analyze the temperature dependence of damage evolution in cryogenic regime as a case study. The damage evolution behavior was classified into regimes of damage nucleation, damage arrest, and damage growth to fracture, irrespective of the deformation temperature in a cryogenic temperature range. Coupled with some high-resolution observations, the damage nucleation and damage arrest sites were identified to be martensite and ferrite, which are common regardless of the deformation temperatures. This indicates that ferrite acted as a damage arrest site even at −180°C. However, a critical strain for damage growth to fracture decreased drastically by decreasing the temperature to −180°C. The distinct reduction in the critical strain is attributed to the transition of ferrite cracking mode from ductile to brittle mechanisms.

Original languageEnglish
Pages (from-to)179-185
Number of pages7
JournalIsij International
Issue number1
Publication statusPublished - 2018
Externally publishedYes


  • Damage arrest
  • Damage quantification
  • Dual-phase steel
  • Ferrite
  • Low temperature
  • Martensite cracking

ASJC Scopus subject areas

  • Mechanics of Materials
  • Mechanical Engineering
  • Metals and Alloys
  • Materials Chemistry


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