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The Effect of δ Phase on the Mechanical Properties of an Inconel 718 Superalloy

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Abstract

The relationship between the δ phase content and the mechanical properties of Inconel 718 superalloy is still uncertain in the scientific literature. This study investigated the effects of the amount of δ phase and of the grain size on the mechanical properties of an aged γ-matrix with γ′ and γ″ precipitates. The material in as-received condition in the form of a forged bar was solution-treated in different conditions and aged according to UNS7718 standard. The microstructures were characterized using optical, scanning, and transmission electron microscopy. Hardness and tensile tests were also conducted. After solution treatment, γ′ and γ″ phases are dissolved and δ phase volume fraction is reduced to a minimum amount only observed by TEM, resulting in an increase of the grain size and a decrease of hardness and strength. After aging, the precipitation of γ′ and γ″ occurs and the amount of δ phase increases. The volume fraction of δ phase varying from 0.30 to 1.38% and the grain size varying from ASTM 7 to 5 do not have a significant effect on the tensile properties and hardness.

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Acknowledgments

The authors would like to thank FINEP (Project No: 01.07.0548-00), CAPES and CNPq for financial support and Celso Barbosa and David Delagostini Jarreta (Villares Metals S.A.) for the material used in this study and for their help during research.

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Authors and Affiliations

  1. Departamento de Engenharia Metalúrgica e de Materiais, Universidade Federal do Rio de Janeiro, C.P. 68505, Rio de Janeiro, RJ, 21945-970, Brazil

    L. C. M. Valle, L. S. Araújo, S. B. Gabriel & L. H. de Almeida

  2. Centro Universitário de Volta Redonda, Volta Redonda, RJ, 27240-560, Brazil

    S. B. Gabriel

  3. Chemical and Materials Department, Université Libre de Bruxelles, Av. F. Roosevelt 50, C. P. 194/03, Brussels, Belgium

    J. Dille

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  1. L. C. M. Valle
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  2. L. S. Araújo
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  5. L. H. de Almeida
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Correspondence to L. C. M. Valle.

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Valle, L.C.M., Araújo, L.S., Gabriel, S.B. et al. The Effect of δ Phase on the Mechanical Properties of an Inconel 718 Superalloy. J. of Materi Eng and Perform 22, 1512–1518 (2013). https://doi.org/10.1007/s11665-012-0433-7

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  • DOI: https://doi.org/10.1007/s11665-012-0433-7

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