Self-stabilization of untransformed austenite by hydrostatic pressure via martensitic transformation

Nobuo Nakada, Yuji Ishibashi, Toshihiro Tsuchiyama, Setsuo Takaki

研究成果: Contribution to journalArticle査読

34 被引用数 (Scopus)

抄録

For improving the understanding of austenite stability in steel, hydrostatic pressure in untransformed austenite that is generated via martensitic transformation was evaluated from macro- and micro-viewpoints, and its effect on austenite stability was investigated in a Fe-27%Ni austenitic alloy. X-ray diffractometry revealed that the lattice parameter of untransformed austenite is continuously decreased via martensitic transformation only when martensite becomes the dominant phase in the microstructure. This suggests that the untransformed austenite is isotropically compressed by the surrounding martensite grains, i.e., hydrostatic pressure is generated in untransformed austenite dynamically at a later stage of martensitic transformation. On the other hand, microscopic strain mapping using the electron backscatter diffraction technique indicated that a finer untransformed austenite grain has a higher hydrostatic pressure, while a high density of dislocations is also introduced in untransformed austenite near the austenite/martensite interface because of lattice-invariant shear characterized by non-thermoelastic martensitic transformation. Furthermore, it was experimentally demonstrated that the hydrostatic pressure stabilizes the untransformed austenite; however, the austenite stabilization effect alone is not large enough to fully explain a large gap between martensite start and finish temperatures in steel.

本文言語英語
ページ(範囲)95-102
ページ数8
ジャーナルActa Materialia
110
DOI
出版ステータス出版済み - 5 15 2016

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Polymers and Plastics
  • Metals and Alloys

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