Impacts of Interface Energies and Transformation Strain from BCC to FCC on Massive-like δ-γ Transformation in Steel

Yoshiya, Masato; Sato, Munetake; Watanabe, Mamoru; Nakajima, Kumiko; Yokoi, Takeshi; Ueshima, Nobufumi; Nagira, Tomoya; Yasuda, Hideyuki

doi:10.1088/1757-899x/84/1/012049

Cited by 10 publications

(7 citation statements)

References 12 publications

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“…Here, T m is melting temperature. Atomistic simulations that were performed by the embedded atom method gave γ grain boundary energy ranges from 0 to 0.4 J m −2 , depending on the degree of misorientation 27 . The phase field model gave an average γ grain boundary energy of 0.37 J m −2 28 .…”

Section: Resultsmentioning

confidence: 99%

Dendrite fragmentation induced by massive-like δ–γ transformation in Fe–C alloys

et al. 2019

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Dendrite arm fragmentation is considered in solidification structure tailoring. Time-resolved and in situ imaging using synchrotron radiation X-rays allows the observation of dendrite arm fragmentation in Fe–C alloys. Here we report a dendrite arm fragmentation mechanism. A massive-like transformation from ferrite to austenite rather than the peritectic reaction occurs during or after ferrite solidification. The transformation produces refined austenite grains and ferrite–austenite boundaries in dendrite arms. The austenite grains are fragmented by the liquid phase that is produced at the grain boundary. In unidirectional solidification, a slight increase in temperature moves the ferrite–austenite interface backwards and promotes detachment of the primary and secondary arms at the δ–γ interface via a reverse peritectic reaction. The results show a massive-like transformation inducing the dendrite arm fragmentation has a role in formation of the solidification structure and the austenite grain structures in the Fe–C alloys.

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Section: Resultsmentioning

confidence: 99%

Dendrite fragmentation induced by massive-like δ–γ transformation in Fe–C alloys

et al. 2019

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“…14) In addition, nucleation of γ phase in δ phase, which is a key issue to understand the massive-like transformation, was also examined by considering interfacial energy and strain induced by the δ -γ transformation with atomistic model and phase field model. [15][16][17] As far as the observations of solidification in Fe-C alloys are concerned, the massive-like transformation is a preferred transformation mode for the undercooled δ phase in carbon steel. The massive-like transformation 12,13) was characterized by following points:…”

Section: Introductionmentioning

confidence: 99%

Selection of the Massive-like δ-γ Transformation due to Nucleation of Metastable δ Phase in Fe-18 Mass%Cr-Ni Alloys with Ni Contents of 8, 11, 14 and 20 Mass%

et al. 2019

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“…The sequence of nucleation and growth has been explained by considering the relationship of interfacial energies. [18][19][20] In our previous observations, 15,16) δ dendrites grew in advance and nucleation of the γ phase hardly occurred even at temperatures below the peritectic temperature when the specimens which had dimensions of 5-10 mm width and 0.1 mm thickness was cooled. As a result, the δ phase was undercooled below the peritectic temperature.…”

Section: Time-resolved and In-situ Observation Of δ -γ Transformationmentioning

confidence: 78%

Time-resolved and In-situ Observation of δ–γ Transformation during Unidirectional Solidification in Fe–C Alloys

et al. 2020

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Time-resolved and in-situ observations using synchrotron radiation X-rays successfully proved that a massive-like transformation, in which the γ phase was produced through the solid-solid transformation and partitioning of substitute elements such as Mn and Si at the δ-γ interface was negligible, 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 near the front of the 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 owing to growth of coarse γ grains. In addition, the observation of the δ-γ interface confirmed that a transition from the diffusion-controlled γ growth to the massive-like γ growth occurred at a growth velocity of 5 μm/s. Thus, the massive-like transformation is dominantly selected in the carbon steel during conventional solidification processes.

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Impacts of Interface Energies and Transformation Strain from BCC to FCC on Massive-like δ-γ Transformation in Steel

Cited by 10 publications

References 12 publications

Dendrite fragmentation induced by massive-like δ–γ transformation in Fe–C alloys

Dendrite fragmentation induced by massive-like δ–γ transformation in Fe–C alloys

Selection of the Massive-like <i>δ</i>-<i>γ</i> Transformation due to Nucleation of Metastable <i>δ</i> Phase in Fe-18 Mass%Cr-Ni Alloys with Ni Contents of 8, 11, 14 and 20 Mass%

Time-resolved and <i>In-situ</i> Observation of <i>δ</i>–<i>γ</i> Transformation during Unidirectional Solidification in Fe–C Alloys

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