Precipitation of γ ″ in Inconel 718 alloy from microstructure to mechanical properties

Alexandre Balan (1) , Michel Perez (2) , Thibaut Chaise (1) , Sophie Cazottes (2) , Didier Bardel (3) , Fabien Corpace (4) , François Pichot (4) , Alexis Deschamps (5) , Frédéric de Geuser (5) , Daniel Nelias (1)

1 LaMCoS - Laboratoire de Mécanique des Contacts et des Structures [Villeurbanne]
2 MATEIS - Matériaux, ingénierie et science [Villeurbanne]
3 FRAMATOME
4 Safran Aircraft Engines
5 SIMaP - Science et Ingénierie des Matériaux et Procédés

This paper presents a coupled approach able to describe γ precipitation evolution and associated yield strength after various heat treatments in Inconel 718 alloy. The precipitation state is modeled via the implementation of classical nucleation and growth theories for plate-shaped particles. The precipitation model is validated through small-angle neutron scattering and transmission electron microscopy experiments. The precipitation size distribution serves as an input parameter to model the yield strength using a micromechanical model based on shear and bypass mechanisms accounting for the particular shapes of the precipitates. Results are in good agreement with measured yield stresses for various precipitation states. A complete simulated TTT diagram of the γ phase with the associated yield strength is proposed. The coupled model is finally applied to a series of non-isothermal treatments representative of welding (or additive manufacturing) from the peak aged state.

Mots clés: Alloy (Inconel) 718; γ phase; Precipitation kinetics; Kampmann-Wagner Numerical (KWN) modeling; Scanning electron microscopy (SEM); Small Angle Neutron Scattering; Structural hardening alloys

Domaines: Science des matériaux [cond-mat.mtrl-sci]

Alexandre Balan, Michel Perez, Thibaut Chaise, Sophie Cazottes, Didier Bardel, et al.. Precipitation of γ ″ in Inconel 718 alloy from microstructure to mechanical properties. Materialia, 2021, 20, pp.101187. ⟨10.1016/j.mtla.2021.101187⟩. ⟨hal-03366225⟩