Time-resolved and in-situ observation of δ-γ transformation during unidirectional solidification in Fe-C alloys

Tomohiro Nishimura, Kohei Morishita, Masato Yoshiya, Tomoya Nagira, Hideyuki Yasuda

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    6 Citations (Scopus)

    Abstract

    Synopsis: Time-resolved and in-situ observations using synchrotron radiation X-rays successfully proved that the massive-like transformation, in which the γ phase was produced through the solid - solid transformation and the partition of substitute elements such as Mn and Si at the δ/γ interface could be negligibly small, was selected in the unidirectional solidification of 0.3 mass%C steel at a pulling rate of 50 μm/s. The massive-like transformation produced fine γ grains in the vicinity of the front of δ/γ interface. The coarse γ grains also grew behind the fine γ grains along the temperature gradient. Distance between the δ/γ front and the advancing front of coarse γ grains was as short as 200 μm. Namely, the fine γ grains disappeared within 10 s by the growth of coarsen γ grains along the temperature gradient. In addition, the observation of the δ/γ interface confirmed that a transition from the diffusion-controlled γ growth to the massive-like growth of γ phase occurred at a growth rate of 5 μm/s. Thus, the massive-like transformation is dominantly selected in the carbon steel during conventional solidification processes.

    Original languageEnglish
    Pages (from-to)168-176
    Number of pages9
    JournalTetsu-To-Hagane/Journal of the Iron and Steel Institute of Japan
    Volume105
    Issue number2
    DOIs
    Publication statusPublished - Feb 2019

    All Science Journal Classification (ASJC) codes

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

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