Effect of the state of carbon on ductility in Fe-0.017mass%C ferritic steel

Nobuyuki Yoshimura, Kohsaku Ushioda, Mitsuharu Yonemura, Motomichi Koyama, Masaki Tanaka, Hiroshi Noguchi

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)


The influence of the state of carbon on ductility in Fe-0.017mass%C alloy was systematically investigated. Moreover, the changes in dislocation density, dislocation substructure, and dislocation character with tensile strain were evaluated using X-ray line profile analysis together with transmission electron microscopy. The solute carbon maintains uniform elongation while simultaneously increasing the ultimate tensile strength by increasing the work-hardening rate; however, post-uniform elongation is significantly impaired by the occurrence of dynamic strain aging (DSA). The coarse intergranular cementite leads to superior uniform elongation; however, post-uniform elongation deteriorates presumably owing to the void formation in the cementite/matrix interface or the fracture of cementite. Meanwhile, the fine transgranular cementite increases the yield strength, thus impairing the uniform elongation; however, it maintains post-uniform elongation. This is because small cementites less than about 1 µm in size do not deteriorate the post-uniform elongation. The solute carbon prominently increases the dislocation density, particularly the edge dislocation density, with tensile strain owing to DSA, leading to the prohibition of dislocation cell structure formation.

Original languageEnglish
Pages (from-to)120-128
Number of pages9
JournalMaterials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing
Publication statusPublished - 2017 Jul 31


  • Cementite
  • Fe-C alloy
  • Solute carbon
  • Strength, ductility
  • Transmission electron microscopy
  • X-ray line profile analysis


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