The effect of interdendritic δ phase on the mechanical properties of Alloy 718 built up by additive manufacturing

Kuo, Yen-Ling; Horikawa, Shota; Kakehi, Koji

doi:10.1016/j.matdes.2016.12.026

Cited by 163 publications

(65 citation statements)

References 19 publications

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“…This as-printed microstructure is consistent with previous reports of L-PBF AM-IN718 [4,[12][13][14][15]17,20]. Chemical segregation due to elemental solutes being ejected to dendrite surfaces encourages localization of oxide, carbide, and Laves particle formation upon the cellular dislocation substructures as a result of rapid cooling rates during additive manufacture, as recently discussed by Yoo et al [20].…”

Section: The As-printed (Ap) Microstructuresupporting

confidence: 90%

“…Subsequent multi-step aging treatments after solution annealing shows improved yield strength (YS) and ultimate tensile strength (UTS) over the as-printed condition, comparable to the same effects these aging steps have on traditionally manufactured IN718 after solution treatments [13,[15][16][17]; namely, the strengthening is attributed to dense g¢ and g″ nanoprecipitate structures.…”

Section: Motivationmentioning

confidence: 68%

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Knowledge of process-structure-property relationships to engineer better heat treatments for laser powder bed fusion additive manufactured Inconel 718

Gallmeyer

Moorthy

Kappes

et al. 2020

Additive Manufacturing

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Dislocation structures, chemical segregation, γ′, γ″, ! precipitates and Laves phase were quantified within the microstructures of Inconel 718 (IN718) produced by laser powder bed fusion additive manufacturing (AM) and subjected to standard, direct aging, and modified multi-step heat treatments. Additionally, heat-treated samples still attached to the build plates vs. those removed were also documented for a standard heat treatment. The effects of the different resulting microstructures on room temperature strengths and elongations to failure is revealed. Knowledge derived from these process-structure-property relationships was used to engineer a super-solvus solution anneal at 1020 ºC for 15 minutes, followed by aging at 720 ºC for 24 hours heat treatment for AM-IN718 that eliminates Laves and δ phases, preserves AM-specific dislocation cells that are shown to be stabilized by MC carbide particles, and precipitates dense γ′ and γ″ nanoparticle populations. This "optimized for AM-IN718 heat treatment" results in superior properties relative to wrought/additively manufactured, then industry standard heat treated IN718: relative increases of 7/10% in yield strength, 2/7% in ultimate strength, and 23/57% in elongation to failure are realized, respectively, regardless of as-built vs. machined surface finishes.

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Section: The As-printed (Ap) Microstructuresupporting

confidence: 90%

Section: Motivationmentioning

confidence: 68%

Knowledge of process-structure-property relationships to engineer better heat treatments for laser powder bed fusion additive manufactured Inconel 718

Gallmeyer

Moorthy

Kappes

et al. 2020

Additive Manufacturing

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“…Besides the microstructure characterizations, focus is also put on the building orientation dependency of mechanical properties. Though the mechanical properties largely depend on the specific process parameters, the general trends and observations are common to all SLM IN718 builds: the horizontally built samples have slightly higher tensile strength than the vertically built samples [160,164,166,194,195].…”

Section: Slm In718mentioning

confidence: 99%

“…The as-manufactured SLM IN718 is mostly associated with lower strengthen than after being heat-treated (solution+ageing or direct ageing) [160,161,163,166,[193][194][195], during which the strengthening phases γ ′ /γ ′′ precipitate and strengthen the matrix. Optimizing the heat treatments have been performed to dissolve the Laves phase and correctly precipitate the δ and strengthening phases γ ′ /γ ′′ .…”

Section: Slm In718mentioning

confidence: 99%

“…The texture in the as-manufactured SLM IN718 can vary with the specific process parameters. Both strong ⟨001⟩ building direction texture [160,167,194] and relatively isotropic crystallographic orientations [165,195,196] have been reported. Besides the microstructure characterizations, focus is also put on the building orientation dependency of mechanical properties.…”

Section: Slm In718mentioning

confidence: 99%

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Additively Manufactured Inconel 718 : Microstructures and Mechanical Properties

Deng

2018

Linköping Studies in Science and Technology. Licentiate Thesis

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Linköping 2018Cover image: A fracture surface of EBM IN718 after tensile test at room temperature.During the course of research underlying this thesis, Dunyong Deng was enrolled in Agora Materiae, a multidiciplinary doctoral program at Linköping University, Sweden. Printed by LiU-Tryck 2018 © Dunyong Deng AbstractAdditive manufacturing (AM), also known as 3D printing, has gained significant interest in aerospace, energy, automotive and medical industries due to its capabilities of manufacturing components that are either prohibitively costly or impossible to manufacture by conventional processes. Among the various additive manufacturing processes for metallic components, electron beam melting (EBM) and selective laser melting (SLM) are two of the most widely used powder bed based processes, and have shown great potential for manufacturing high-end critical components, such as turbine blades and customized medical implants. The futures of the EBM and SLM are doubtlessly promising, but to fully realize their potentials there are still many challenges to overcome.Inconel 718 (IN718) is a nickel-base superalloy and has impressive combination of good mechanical properties and low cost. Though IN718 is being mostly used as a turbine disk material now, the initial introduction of IN718 was to overcome the poor weldability of superalloys in 1960s, since sluggish precipitation of strengthening phases γ ′ /γ ′′ enables good resistance to strain-age cracking during welding or post weld heat treatment. Given the similarity between AM and welding processes, IN718 has been widely applied to the metallic AM field to facilitate the understandings of process-microstructure-property relationships.The work presented in this licentiate thesis aims to better understand microstructures and mechanical properties EBM and SLM IN718, which have not been systematically investigated. Microstructures of EBM and SLM IN718 have been characterized with scanning electron microscopy (SEM), transmission electron microscopy (TEM) and correlated with the process conditions. Monotonic mechanical properties (e.g., Vickers microhardness and tensile properties) have also been measured and rationalized with regards to the microstructure evolutions before and after heat treatments.For EBM IN718, the results show the microstructure is not homogeneous but dependant on the location in the components, and the anisotropic mechanical properties are probably attributed to alignment of porosities rather than texture.iii Post heat treatment can slightly increase the mechanical strength compared to the as-manufactured condition but does not alter the anisotropy. SLM IN718 shows significantly different microstructure and mechanical properties to EBM IN718. The as-manufactured SLM IN718 has very fine dendritic microstructure and Laves phases in the interdendrites, and is "work-hardened" by the residual strains and dislocations present in the material. Mechanical properties are different between horizontally and vertically built samples, and heat treatment can m...

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Microstructure Evolution and Powder Effects

2024

Metallic Powders for Additive Manufacturing

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The effect of interdendritic δ phase on the mechanical properties of Alloy 718 built up by additive manufacturing

Cited by 163 publications

References 19 publications

Knowledge of process-structure-property relationships to engineer better heat treatments for laser powder bed fusion additive manufactured Inconel 718

Knowledge of process-structure-property relationships to engineer better heat treatments for laser powder bed fusion additive manufactured Inconel 718

Additively Manufactured Inconel 718 : Microstructures and Mechanical Properties

Microstructure Evolution and Powder Effects

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