Is there an optimal grain size for creep resistance in Ni-based disk superalloys?

Louis Thébaud 1 Patrick Villechaise 1 Coraline Crozet Alexandre Devaux 2 Denis Béchet 3, 4 Jean-Michel Franchet 5 Anne-Laure Rouffié 6 Michael Mills 7 Jonathan Cormier 1
1 ENDO - ENDOmmagement et durabilité ENDO
Département Physique et Mécanique des Matériaux - Département Physique et Mécanique des Matériaux
2 Aubert & Duval
3 LS2N - Laboratoire des Sciences du Numérique de Nantes
4 TALN - Traitement Automatique du Langage Naturel
LS2N - Laboratoire des Sciences du Numérique de Nantes
5 SNECMA Gennevilliers [Colombes]
6 Safran Tech
7 Human Interface Group
Abstract : The high temperature creep properties of next generation cast and wrought AD730 superalloy have been investigated taking into consideration three microstructural parameters: the grain size, the presence of grain boundaries and the γ′ precipitates size and distribution. Definitive analysis of the influence of the grain boundaries and γ′ precipitates size distribution has been enabled by the study of single crystalline versions of the polycrystalline alloys studied. At high temperature (equal to or in excess of 850 °C), the grain size controls creep properties. Comparisons between polycrystalline and single crystalline specimens indicate that the grain boundaries provide a strengthening effect, especially in the small strain regime. At intermediate temperature (700 °C), the γ′ precipitates size is the main creep-rate controlling parameter. In this temperature domain, creep strength seems to be mainly controlled by dislocation motion. A very striking grain boundary strengthening mechanism is observed at small creep strain and intermediate temperature.
Keywords : Superalloy Creep Grain boundaries γ′ precipitation
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https://hal.archives-ouvertes.fr/hal-02303657
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Submitted on : Wednesday, October 2, 2019 - 2:45:29 PM
Last modification on : Tuesday, November 5, 2019 - 1:08:19 AM

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Louis Thébaud, Patrick Villechaise, Coraline Crozet, Alexandre Devaux, Denis Béchet, et al.. Is there an optimal grain size for creep resistance in Ni-based disk superalloys?. Materials Science and Engineering: A, Elsevier, 2018, 716, pp.274-283. ⟨10.1016/j.msea.2017.12.104⟩. ⟨hal-02303657⟩

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