Creep–Fatigue Interaction of Inconel 718 Manufactured by Electron Beam Melting

Electron beam melting of Ni‐base superalloy Inconel 718 allows producing a columnar‐grained microstructure with a pronounced texture, which offers exceptional resistance against high‐temperature loading with severe creep–fatigue interaction arising in components of aircraft jet engines. This study c...

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Bibliographic Details
Published in:Advanced engineering materials 2023-08, Vol.25 (16), p.n/a
Main Authors: Guth, Stefan, Babinský, Tomáš, Antusch, Steffen, Klein, Alexander, Kuntz, Daniel, Šulák, Ivo
Format: Article
Language:English
Subjects:
additive manufacturing
creep–fatigue interaction
damage mechanisms
Inconel 718
thermomechanical fatigue
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Summary:Electron beam melting of Ni‐base superalloy Inconel 718 allows producing a columnar‐grained microstructure with a pronounced texture, which offers exceptional resistance against high‐temperature loading with severe creep–fatigue interaction arising in components of aircraft jet engines. This study considers the deformation, damage, and lifetime behavior of electron‐beam‐melted Inconel 718 under in‐phase thermomechanical fatigue loading with varying amounts of creep–fatigue interaction. Strain‐controlled thermomechanical fatigue tests with equal‐ramp cycles, slow–fast cycles, and dwell time cycles are conducted in the temperature range from 300 to 650 °C. Results show that both dwell time and slow–fast cycles promote intergranular cracking, gradual tensile stress relaxation, as well as precipitate dissolution and coarsening giving rise to cyclic softening. The interplay of these mechanisms leads to increased lifetimes in both dwell time and slow–fast tests compared to equal ramp tests at higher strain amplitudes. Conversely, at lower mechanical strain amplitudes, the opposite is observed. A comparison with results of conventional Inconel 718 indicates that the electron‐beam‐melted material exhibits superior resistance against strain‐controlled loading at elevated temperatures such as thermomechanical fatigue. Thermomechanical fatigue tests with varying amounts of creep–fatigue interaction show that electron‐beam‐melted Ni‐base alloy Inconel 718 exhibits excellent creep‐fatigue resistance due to its columnar‐grained microstructure with strong texture along the loading direction. The predominantly intergranular damage concentrates in areas with less elongate grains suggesting that the manufacturing strategy may be optimized to increase the creep‐fatigue resistance even further.
ISSN:1438-1656
1527-2648
DOI:10.1002/adem.202300294