Effects of precipitation phases on the hydrogen embrittlement sensitivity of Inconel 718

Liu, Liufa; Tanaka, Katsumi; Hirose, Akio; Kobayashi, Kojiro F.

doi:10.1016/s1468-6996(02)00039-6

Cited by 79 publications

(56 citation statements)

References 24 publications

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“…[16] It has been shown that the d phase precipitates, whether formed at the grain boundaries or within the matrix, influence the mechanical properties like fatigue, [17][18][19][20] stress rupture, and hot working as well as hydrogen embrittlement sensitivity in environments with high partial pressure of hydrogen. [21] Laves phase is a hexagonally close packed (hcp) phase and is generally accepted to be of the form (Ni,Fe,Cr) 2 (Nb,Mo,Ti). [22,23] The presence of the Laves phase, reported in the early literature in wrought materials, is a result of incomplete homogenization of the alloy prior to final heat treatments.…”

Section: Introductionmentioning

confidence: 99%

“…[46][47][48][49] They also act as deep traps of hydrogen in sour and hydrogen containing environments and thus promote hydrogen embrittlement. [21] Therefore, the identification and characterization of this phase help the understanding of the grain size distribution and also the hydrogen embrittlement of alloy 718 in harsh hydrogen containing environments. In the current work, we carry out the systematic approach on the identification of M 23 C 6 carbides in alloy 718, its precipitation and dissolution behavior as well as the effect of strain on the precipitation of M 23 C 6 .…”

Section: Introductionmentioning

confidence: 99%

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Identification of Mo-Rich M23C6 Carbides in Alloy 718

Aghajani¹,

Tewes²,

Parsa

et al. 2016

Metall Mater Trans A

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In the present study, we systematically identify and characterize a (Nb, Mo)-rich M 23 C 6 type of M 23 C 6 carbide with a lattice parameter of 1.094 nm in alloy 718 for the first time using a combination of selected area electron diffraction pattern and powder X-ray diffraction analysis. The time-temperature-precipitation diagrams of the precipitates in both annealed and strained conditions are obtained by particle analysis using an automated scanning electron microscopy method. (Nb, Mo)-rich M 23 C 6 carbides first precipitate after 24 hours at 1223 K (950°C) annealing, while they form after 10 minutes at 1273 K (1000°C) in the strained condition. This correlates with the excess dislocations produce during deformation.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Identification of Mo-Rich M23C6 Carbides in Alloy 718

Aghajani¹,

Tewes²,

Parsa

et al. 2016

Metall Mater Trans A

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“…We used the simple well known formula: Using data and procedure proposed by Liu and coworkers [10] we have calculate the values of diffusion coefficients for temperature 750 and 850K as equal 1,6510 -10 and 4,1710 -10 m 2 /s respectively. On the basis of these calculation it was possible evaluate the depth of hydrogen diffusion as: t 750K ≈ 0,04m and 0,067m respectively.…”

Section: Discussionmentioning

confidence: 99%

Degradation of Creep Resistant Ni - Alloy During Aging at Elevated Temperature Part II: Structure Investigations

Kaczorowski¹,

Skoczylas²,

Krzyńska³

2015

Archives of Foundry Engineering

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The results of structure observations of Ni base superalloy subjected to long-term influence of high pressure hydrogen atmosphere at 750K and 850K are presented. The structure investigation were carried out using conventional light-, scanning-(SEM) and transmission electron microscopy (TEM). The results presented here are supplementary to the mechanical studies given in part I of this investigations. The results of study concerning mechanical properties degradation and structure observations show that the differences in mechanical properties of alloy subjected different temperature are caused by more advanced processes of structure degradation during long-term aging at 850K, compare to that at 750K. Higher service temperature leads to formation of large precipitates of δ phase. The nucleation and growth of needle-and/or plate-like, relative large delta precipitates proceed probably at expense strengthening γ" phases. Moreover, it can't be excluded that the least stable γ" phase is replaced with more stable γ' precipitates. TEM observations have disclosed differences in dislocation structure of alloy aged at 750K and 850K. The dislocation observed in alloy subjected to 750K are were seldom observed only, while in that serviced at high stress and 850K dislocation array and dislocation cell structure was typical.

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“…Despite its advantages, this alloy is susceptible to hydrogen embrittlement caused by the penetration of hydrogen resulting in degradation and catastrophic failure [2,3]. It is well-known that grain boundaries play an essential role in hydrogen-induced cracking and embrittlement in polycrystalline metallic materials [4][5][6][7][8][9][10][11]. It has been reported that at a high hydrogen concentration, the δ-phase in IN718 dramatically reduces the ductility of the alloy [12].…”

Section: Introductionmentioning

confidence: 99%

Hydrogen Permeation, and Mechanical and Tribological Behavior, of CrNx Coatings Deposited at Various Bias Voltages on IN718 by Direct Current Reactive Sputtering

et al. 2018

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In the current work, the microstructure, hydrogen permeability, and properties of chromium nitride (CrN x ) thin films deposited on the Inconel 718 superalloy using direct current reactive sputtering are investigated. The influence of the substrate bias voltage on the crystal structure, mechanical, and tribological properties before and after hydrogen exposure was studied. It was found that increasing the substrate bias voltage leads to densification of the coating. X-ray diffraction (XRD) results reveal a change from mixed fcc-CrN + hcp-Cr 2 N to the approximately stoichiometric hcp-Cr 2 N phase with increasing substrate bias confirmed by wavelength-dispersive X-ray spectroscopy (WDS). The texture coefficients of (113), (110), and (111) planes vary significantly with increasing substrate bias voltage. The hydrogen permeability was measured by gas-phase hydrogenation. The CrN coating deposited at 60 V with mixed c-CrN and (113) textured hcp-Cr 2 N phases exhibits the lowest hydrogen absorption at 873 K. It is suggested that the crystal orientation is only one parameter influencing the permeation resistance of the CrN x coating together with the film structure, the presence of mixing phases, and the packing density of the structure. After hydrogenation, the hardness increased for all coatings, which could be related to the formation of a Cr 2 O 3 oxide film on the surface, as well as the defect formation after hydrogen loading. Tribological tests reveal that hydrogenation leads to a decrease of the friction coefficient by up to 40%. The lowest value of 0.25 ± 0.02 was reached for the CrN x coating deposited at 60 V after hydrogenation.

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Effects of precipitation phases on the hydrogen embrittlement sensitivity of Inconel 718

Cited by 79 publications

References 24 publications

Identification of Mo-Rich M23C6 Carbides in Alloy 718

Identification of Mo-Rich M23C6 Carbides in Alloy 718

Degradation of Creep Resistant Ni - Alloy During Aging at Elevated Temperature Part II: Structure Investigations

Hydrogen Permeation, and Mechanical and Tribological Behavior, of CrNx Coatings Deposited at Various Bias Voltages on IN718 by Direct Current Reactive Sputtering

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