Interpretation of cryogenic-temperature Charpy fracture initiation and propagation energies by microstructural evolution occurring during dynamic compressive test of austenitic Fe-(0.4,1.0)C-18Mn steels

Hyunmin Kim, Jaeyoung Park, Joong Eun Jung, Seok S Sohn, Sunghak Lee

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

In the present study, Charpy impact energy (E T ) composed of fracture initiation energy (E I ) and propagation energy (E P ) of austenitic Fe-(0.4,1.0)C-18Mn steels was evaluated in the temperature range from room to cryogenic temperatures by an instrumented Charpy impact tester, and was interpreted by microstructural evolution of dynamically compressed specimens. In the 1.0C-18Mn steel, the E I and E P decreased slightly with decreasing temperature, but the E P /E T ratio was kept to be about 0.5. In the 0.4C-18Mn steel, the E I remained almost constant or slightly decreased with decreasing temperature, while the E P /E T ratio steadily decreased, thereby leading to the lower (about 30%) cryogenic-temperature E T than that of the 1.0C-18Mn steel. Under the dynamic compressive loading, a considerable number of ε-martensites were formed in the 0.4C-18Mn steel, whereas they were not found in the 1.0C-18Mn steel, and their volume fractions increased steadily with decreasing temperature. This γ→ε-martensite transformation was attributed to the decrease in stacking fault energy, and resulted in the very low E P and resultant E T .

Original languageEnglish
Pages (from-to)340-347
Number of pages8
JournalMaterials Science and Engineering A
Volume641
DOIs
Publication statusPublished - 2015 Jul 4
Externally publishedYes

Keywords

  • Cryogenic temperature
  • Dynamic compressive test
  • High-Mn steel
  • Instrumented Charpy impact toughness
  • Martensitic transformation
  • Twin

ASJC Scopus subject areas

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

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