Investigation using 4D-CT of massive-like transformation from the δ to γ phase during and after δ-solidification in carbon steels

Hideyuki Yasuda, Takahiro Hashimoto, Naoki Sei, Kohei Morishita, Masato Yoshiya

Research output: Contribution to journalConference article

1 Citation (Scopus)

Abstract

For a long time, the γ phase in metallic alloys has seemed to be produced through a peritectic reaction between the δ and liquid phases. However, direct observations have shown that a massive-like transformation, in which the δ phase transforms into the γ phase in the solid state, is dominant during or after solidification of the δ phase in carbon steels. To characterize such massive-like transformation, we use time-resolved tomography (4D-CT) to demonstrate the volume change during cooling from the melt and the crystallographic orientation relationship between the δ and γ phases. The volume changes from solidification and from the massive-like transformation from the δ to the γ phase were -3% and -0.5%, respectively. The transformation from the δ to the γ phase finished quickly, as demonstrated by the volume change. Fine γ grains were produced even in a single δ grain through the massive-like transformation. Also, the refined γ grains showed a wide crystallographic distribution.

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Carbon steel
Solidification
Tomography
Cooling
Liquids

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Engineering(all)

Cite this

Investigation using 4D-CT of massive-like transformation from the δ to γ phase during and after δ-solidification in carbon steels. / Yasuda, Hideyuki; Hashimoto, Takahiro; Sei, Naoki; Morishita, Kohei; Yoshiya, Masato.

In: IOP Conference Series: Materials Science and Engineering, Vol. 529, No. 1, 012013, 17.06.2019.

Research output: Contribution to journalConference article

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abstract = "For a long time, the γ phase in metallic alloys has seemed to be produced through a peritectic reaction between the δ and liquid phases. However, direct observations have shown that a massive-like transformation, in which the δ phase transforms into the γ phase in the solid state, is dominant during or after solidification of the δ phase in carbon steels. To characterize such massive-like transformation, we use time-resolved tomography (4D-CT) to demonstrate the volume change during cooling from the melt and the crystallographic orientation relationship between the δ and γ phases. The volume changes from solidification and from the massive-like transformation from the δ to the γ phase were -3{\%} and -0.5{\%}, respectively. The transformation from the δ to the γ phase finished quickly, as demonstrated by the volume change. Fine γ grains were produced even in a single δ grain through the massive-like transformation. Also, the refined γ grains showed a wide crystallographic distribution.",
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AU - Yasuda, Hideyuki

AU - Hashimoto, Takahiro

AU - Sei, Naoki

AU - Morishita, Kohei

AU - Yoshiya, Masato

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N2 - For a long time, the γ phase in metallic alloys has seemed to be produced through a peritectic reaction between the δ and liquid phases. However, direct observations have shown that a massive-like transformation, in which the δ phase transforms into the γ phase in the solid state, is dominant during or after solidification of the δ phase in carbon steels. To characterize such massive-like transformation, we use time-resolved tomography (4D-CT) to demonstrate the volume change during cooling from the melt and the crystallographic orientation relationship between the δ and γ phases. The volume changes from solidification and from the massive-like transformation from the δ to the γ phase were -3% and -0.5%, respectively. The transformation from the δ to the γ phase finished quickly, as demonstrated by the volume change. Fine γ grains were produced even in a single δ grain through the massive-like transformation. Also, the refined γ grains showed a wide crystallographic distribution.

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