Phase transformations and grain growth behaviors in superalloy 718

Ruan, Jun; Ueshima, Nobufumi; Oikawa, Katsunari

doi:10.1016/j.jallcom.2017.11.327

Cited by 42 publications

(7 citation statements)

References 39 publications

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“…The solidification of Inconel 718 superalloy generally has the following steps (Ruan et al , 2018; Knorovsky et al ,1989): L→ γ+L→ (γ+NbC) + L→ γ+L → γ+Laves. As stated earlier, the PAAM can also be regarded as a micro-casting process.…”

Section: Resultsmentioning

confidence: 99%

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Research on microstructure and mechanical properties of hybrid plasma arc and micro-rolling additive manufacturing of Inconel 718 superalloy

Chen

Wang

Zhang

et al. 2022

RPJ

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Purpose The purpose of this paper is to study the influence of different rolling deformation parameters on the morphology, microstructure and mechanical properties of Inconel 718 superalloy in hybrid plasma arc and micro-rolling (HPAMR) additive manufacturing. Design/methodology/approach In this paper, different deformation strains are designed, which are as-deposited, 15% and 30%. Two straight walls are fabricated by HPAMR for each kind of deformation. One wall underwent post-deposition heat treatment, and the other wall is treated without heat treatment. These samples are further investigated to evaluate the effects of deformation on the morphology, microstructure and mechanical properties. Findings As compared to as-deposited samples, the morphology can be significantly improved, the generation of defects and microporosity inside the alloy can be suppressed, and finer equiaxed crystals can be obtained with deformation of 30%. With heat treatment and 30% deformation, the Laves phase at the grain boundary is completely disappearing, more γ” and γ' strengthening phase is precipitated in the crystal and the size of the strengthening phase is smaller. Mechanical properties have been significantly improved. Practical implications HPAMR technology is used to successfully manufacture Inconel 718 superalloy aero-engine casing. Originality/value Compared with plasma arc additive manufacturing, HPAMR technology adds a rolling process, which can effectively improve the morphology of walls, refine internal grains, eliminate defects and microporosity, increase precipitation of strengthening phase and improve mechanical properties. It provides an optional manufacturing method for the integrated manufacturing of Inconel 718 parts.

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Section: Resultsmentioning

confidence: 99%

“…The solidification of Inconel 718 superalloy generally has the following steps (Ruan et al, 2018;Knorovsky et al,1989):…”

Section: Microstructurementioning

confidence: 99%

Research on microstructure and mechanical properties of hybrid plasma arc and micro-rolling additive manufacturing of Inconel 718 superalloy

Chen

Wang

Zhang

et al. 2022

RPJ

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“…20,21) The temperature of the  solvus for superalloy 718 ranges from 950 to 1010 °C. 22) The higher the heat-treatment temperature of superalloy 718 in the range of 1050-1200 °C, the higher is the grain growth rate, 23) resulting in inferior mechanical properties. The application of strain to metals, that are hardened by precipitation during hot working under specific conditions, induces SIDP.…”

Section: Introductionmentioning

confidence: 99%

Flow Curve of Superalloy 718 under Hot Forming in a Region of <i>γ</i>” Precipitation

et al. 2023

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This study aims to formulate a constitutive equation to accurately determine the flow stress of superalloy 718 for effective production of gas turbine disks. A hot-compression test with superalloy 718 at temperatures ranging from 900 to 1000 °C, a reduction rate of 67%, and strain rates of 0.1, 1, and 10 s −1 , respectively, was conducted to analyze the flow stress in the dynamic precipitation region. An accurate flow stress curve was obtained for each strain rate and initial temperature. The flow curves obtained at a deformation temperature of 900 °C and strain rates of 0.1 and 1 s −1 , represent a combination of work-hardening and dynamic recovery. Dynamic recrystallization (DRX) behavior was observed under other deformation conditions. At a deformation temperature of 950 °C and each strain rate, the strain at the onset of DRX ( c ) decreases, and DRX tends to occur rapidly. In addition, the steady-state stress at a strain rate of 1 s −1 was greater than that at a higher strain rate of 10 s −1 . The lowest steady-state stress among all the experimental conditions was observed at a strain rate of 10 s −1 . This may be attributed to the role of nucleation sites, precipitation hardening caused by dynamically precipitated " phases at approximately 950 °C and a strain rate of 1 s −1 , and dynamic softening effects due to significant heat generated by deformation at a strain rate of 10 s −1 . A new constitutive equation for the generalized flow curve of superalloy 718 was obtained by considering these metallurgical phenomena.

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“…Ni-based superalloys have wide applications in high-temperature components, such as aircraft engines and gas turbines [8][9][10][11][12]. Thus, the study of grain growth behavior in Ni-based superalloys is of interest to many researchers [13][14][15][16][17][18]. Ruan et al [13] found that grain growth in IN718 can be retarded by NbC and TiN phases due to Ostwald ripening.…”

Section: Introductionmentioning

confidence: 99%

“…Thus, the study of grain growth behavior in Ni-based superalloys is of interest to many researchers [13][14][15][16][17][18]. Ruan et al [13] found that grain growth in IN718 can be retarded by NbC and TiN phases due to Ostwald ripening. Lee et al [14] found that the grain boundary structure can become rough at high temperatures, and it has a significant influence on the grain growth in a model Ni-based superalloy.…”

Section: Introductionmentioning

confidence: 99%

Study of Grain Growth in a Ni-Based Superalloy by Experiments and Cellular Automaton Model

Liu

et al. 2021

Materials

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The grain growth behavior in a typical Ni-based superalloy was investigated using isothermal heat treatment experiments over a holding temperature range of 1353–1473 K. The experimental results showed that the grain structure continuously coarsened as the holding time and holding temperature increased during heat treatment. A classical parabolic grain growth model was used to explore the mechanism of grain growth under experimental conditions. The grain growth exponent was found to be slightly above 2. This indicates that the current grain growth in the studied superalloy is mainly governed by grain boundary migration with a minor pinning effect from the precipitates. Then, the grain growth in the studied superalloy during isothermal heat treatment was modelled by a cellular automaton (CA) with deterministic state switch rules. The microscale kinetics of grain growth is described by the correlation between the moving velocity and curvature of the grain boundary. The local grain boundary curvature is well evaluated by a template disk method. The grain boundary mobility was found to increase with increasing temperature. The relationship between the grain boundary mobility and temperature has been established. The developed CA model is capable of capturing the dependence of the grain size on the holding time under different holding temperatures.

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Phase transformations and grain growth behaviors in superalloy 718

Cited by 42 publications

References 39 publications

Research on microstructure and mechanical properties of hybrid plasma arc and micro-rolling additive manufacturing of Inconel 718 superalloy

Research on microstructure and mechanical properties of hybrid plasma arc and micro-rolling additive manufacturing of Inconel 718 superalloy

Flow Curve of Superalloy 718 under Hot Forming in a Region of <i>γ</i>” Precipitation

Study of Grain Growth in a Ni-Based Superalloy by Experiments and Cellular Automaton Model

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