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σ-Phase Formation in Super Austenitic Stainless Steel During Directional Solidification and Subsequent Phase Transformations

Marin, Raphaël and Combeau, Hervé and Zollinger, Julien and Dehmas, Moukrane and Rouat, Bernard and Lamontagne, Aude and Loukachenko, Natalia and Lhenry-Robert, Lucile σ-Phase Formation in Super Austenitic Stainless Steel During Directional Solidification and Subsequent Phase Transformations. (2020) Metallurgical and Materials Transactions A, 51 (7). 3526-3534. ISSN 1073-5623

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Official URL: https://doi.org/10.1007/s11661-020-05794-1


The solidification path and the σ-phase precipitation mechanism in the S31254 (UNS designation) steel are investigated thanks to Quenching during Directional Solidification (QDS) experiments accompanied by scanning electron microscopy observations and electron backscattered diffraction (EBSD) analysis. Considering experimental conditions, the γ-austenite is found to be the primary solidifying phase (1430 °C), followed by δ-ferrite (1400 °C, ≈ 87 pct solid fraction). The σ-phase appears in the solid-state through the eutectoid decomposition of the δ-ferrite: δ → σ + γ2 (1210 °C), whereas the σ-phase is predicted to form from the austenite at 1096 °C in equilibrium conditions. The resulting temperatures of solidification path and phase transformation are compared with Gulliver–Scheil model and equilibrium calculations predicted using Thermo-Calc© software. It is shown that the thermodynamics calculations agree with experimental results of solidification path. The EBSD analysis show that the δ-ferrite has δNW2 ORs with the σ-phase.

Item Type:Article
HAL Id:hal-02752428
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution:Other partners > Arcelor Mittal Research (FRANCE)
French research institutions > Centre National de la Recherche Scientifique - CNRS (FRANCE)
Université de Toulouse > Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE)
Université de Toulouse > Université Toulouse III - Paul Sabatier - UT3 (FRANCE)
Other partners > Université de Lorraine (FRANCE)
Laboratory name:
Industeel and ANRT under a CIFRE Ph.D. fellowship
Deposited On:09 Nov 2020 09:27

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