Effect of standard heat treatment on the microstructure and mechanical properties of selective laser melting manufactured Inconel 718 superalloy

Zhang, Dongyun; Niu, Wen Jie; Cao, Xuanyang; Liu, Zhen

doi:10.1016/j.msea.2015.06.021

Cited by 572 publications

(229 citation statements)

References 21 publications

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“…EDS analysis showed that the atomic ratio of Fe:Nb in the white plate-like phase observed in homogenized specimens (Spot 5 in Figure 6) is 2.5:1. Although the plate-like phase could not be detected by X-ray diffraction due to a relatively small amount of precipitates, its morphology and composition are comparable with the Laves phase reported in the literature [3,19]. Qi et al [3] reported the partial dissolution of the Laves phase during solution treatment at 980 °C of laser net shape manufactured specimens.…”

Section: Phase Analysis Of Heat-treated Inconel 718supporting

confidence: 62%

Microstructural and Microhardness Evolution from Homogenization and Hot Isostatic Pressing on Selective Laser Melted Inconel 718: Structure, Texture, and Phases

Seede

Mostafa

Braïlovski

et al. 2018

JMMP

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Abstract:In this work, the microstructure, texture, phases, and microhardness of 45 • printed (with respect to the build direction) homogenized, and hot isostatically pressed (HIP) cylindrical IN718 specimens are investigated. Phase morphology, grain size, microhardness, and crystallographic texture at the bottom of each specimen differ from those of the top due to changes in cooling rate. High cooling rates during the printing process generated a columnar grain structure parallel to the building direction in the as-printed condition with a texture transition from (001) orientation at the bottom of the specimen to (111) orientation towards the specimen top based on EBSD analysis. A mixed columnar and equiaxed grain structure associated with about a 15% reduction in texture is achieved after homogenization treatment. HIP treatment caused significant grain coarsening, and engendered equiaxed grains with an average diameter of 154.8 µm. These treatments promoted the growth of δ-phase (Ni 3 Nb) and MC-type brittle (Ti, Nb)C carbides at grain boundaries. Laves phase (Fe 2 Nb) was also observed in the as-printed and homogenized specimens. Ostwald ripening of (Ti, Nb)C carbides caused excessive grain growth at the bottom of the HIPed IN718 specimens, while smaller grains were observed at their top. Microhardness in the as-fabricated specimens was 236.9 HV and increased in the homogenized specimens by 19.3% to 282.6 HV due to more even distribution of secondary precipitates, and the nucleation of smaller grains. A 36.1% reduction in microhardness to 180.5 HV was found in the HIPed condition due to γ phase dissolution and differences in grain morphology.

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Section: Phase Analysis Of Heat-treated Inconel 718supporting

confidence: 62%

Microstructural and Microhardness Evolution from Homogenization and Hot Isostatic Pressing on Selective Laser Melted Inconel 718: Structure, Texture, and Phases

Seede

Mostafa

Braïlovski

et al. 2018

JMMP

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“…Differently, the subsequently published TEM work by Zhang et al [163] and Choi et al [192] showed that the asmanufactured SLM IN718 has very few γ ′ /γ ′′ precipitated in matrix due to the high temperature gradient and rapid solidification rate, but instead large amount of fine Laves phases and carbides can be found as well as dislocation sub-grain structures.…”

Section: Slm In718mentioning

confidence: 96%

“…As that for titanium alloys, employing SLM or EBM to manufacture Ni-base superalloys would depend on the specific case or application, since each process has its pros and cons. So far, the Ni-base superalloys applied to SLM are mainly the weldable ones, i.e., IN718 [113,[160][161][162][163][164][165][166][167], IN625 [79,80,168,169], Hastelloy X [170][171][172][173][174], Nimonic 263 [110], which have low additions of both Ti and Al and are less susceptible to strain age cracking. Expansion to the less-weldable Ni-base superalloys has also been attempted, such as IN939 [175], IN100 [176], IN738LC [177][178][179][180][181], CM247LC [114,[182][183][184] and Rene 142 [81].…”

Section: Materials Manufactured With Slmmentioning

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%

“…Optimizing the heat treatments have been performed to dissolve the Laves phase and correctly precipitate the δ and strengthening phases γ ′ /γ ′′ . Higher homogenization/solution temperature or longer homogenization/solution holding time is necessary for removing the Nb segregation and improving mechanical properties [163,166]. The texture in the as-manufactured SLM IN718 can vary with the specific process parameters.…”

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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Post‐processing in Additive Manufacturing

BACROIX

2023

Additive Manufacturing of Metal Alloys 2

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Effect of standard heat treatment on the microstructure and mechanical properties of selective laser melting manufactured Inconel 718 superalloy

Cited by 572 publications

References 21 publications

Microstructural and Microhardness Evolution from Homogenization and Hot Isostatic Pressing on Selective Laser Melted Inconel 718: Structure, Texture, and Phases

Microstructural and Microhardness Evolution from Homogenization and Hot Isostatic Pressing on Selective Laser Melted Inconel 718: Structure, Texture, and Phases

Additively Manufactured Inconel 718 : Microstructures and Mechanical Properties

Post‐processing in Additive Manufacturing

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