Carbon enrichment of austenite during ferrite-bainite transformation in low-alloysteel

Shun Tanaka, Hiroyuki Shirahata, Genichi Shigesato, Manabu Takahashi

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1 Citation (Scopus)


The bainitic transformation kinetics and carbon enrichment of austenite during isothermal holding at 723-923 K were investigated for an Fe-0.1mass%C-0.5mass%Si-2.0mass%Mn alloy. The transformation progressed rapidly until approximately 50 s, after which transformation stasis was observed at 823 K. The carbon concentration of austenite increased as the transformation proceeded, and showed an almost constant value during stasis. It reached approximately 0.45-0.50% at 823 K, which corresponds to the carbon concentration at the T0 ' composition with an additional strain energy of 100 J/mol associated with the transformation. After stasis, a slight increase in the ferrite or bainitic ferrite fraction was observed. The carbon concentration of austenite also increased and reached approximately 0.60%, clearly exceeding the carbon concentration at the T0 composition. These results imply that at the first stage, the bainite transformation occurs and shows the incomplete transformation, following which at the second stage, diffusional ferrite transformation proceeds. The additional strain energy associated with the transformation calculated from the carbon concentration at stasis due to the incomplete bainite transformation tends to decrease as the holding temperature increases. This indicates that strain relaxation due to the transformation occurred at higher holding temperatures.

Original languageEnglish
Pages (from-to)835-844
Number of pages10
JournalTetsu-To-Hagane/Journal of the Iron and Steel Institute of Japan
Issue number10
Publication statusPublished - Oct 2021

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics
  • Physical and Theoretical Chemistry
  • Metals and Alloys
  • Materials Chemistry


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