Effect of post-treatment on the microstructure and high-temperature oxidation behaviour of additively manufactured inconel 718 alloy

Kang, Yeon-Ji; Yang, Sangsun; Kim, Young-Kyun; AlMangour, Bandar; Lee, Kee‐Ahn

doi:10.1016/j.corsci.2019.06.030

Cited by 86 publications

(46 citation statements)

References 31 publications

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“…Unlike conventional manufacturing processes (casting, machining, etc. ), which have shape limitations, AM has almost no geometric constraints, which allows the manufacturing of a variety of complex shapes 29,30 . Because of this characteristic, it is possible to manufacture components that were difficult to manufacture before, as well as high-performance parts for use in aerospace, defense, automotive and biomedical fields.…”

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confidence: 99%

Superior Temperature-Dependent Mechanical Properties and Deformation Behavior of Equiatomic CoCrFeMnNi High-Entropy Alloy Additively Manufactured by Selective Laser Melting

Kim

Yang

Lee

2020

Sci Rep

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The microstructure, temperature-dependent mechanical properties and deformation behaviors of equiatomic CoCrFeMnNi high-entropy alloy (HEA) additively manufactured by selective laser melting (SLM) were investigated. SLM-built HEA had a face-centered cubic (FCC) single-phase random solid solution. In addition, SLM-built HEA was composed of epitaxial growth grains, dislocation network and nano-sized oxides. Room- and high-temperature compression tests confirmed that SLM-built HEA has outstanding mechanical properties in all temperature ranges compared to equiatomic CoCrFeMnNi HEAs reported up to the present. The excellent mechanical properties of SLM-built HEA were achieved with fine grains, high dislocation density and fine precipitates at low temperatures (25 °C to 600 °C), and by high dislocation density and fine precipitates at high temperatures (700 °C or higher). On the other hand, the deformation microstructure showed that slip and deformation twins are the main deformation mechanisms from 25 °C to 600 °C, and slip and partial recrystallization are the main deformation mechanisms above 700 °C. Based on the above findings, this study also discusses correlations among the microstructure, superior mechanical properties and deformation mechanisms of SLM-built equiatomic CoCrFeMnNi HEA.

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confidence: 99%

Superior Temperature-Dependent Mechanical Properties and Deformation Behavior of Equiatomic CoCrFeMnNi High-Entropy Alloy Additively Manufactured by Selective Laser Melting

Kim

Yang

Lee

2020

Sci Rep

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“…They found that Cr depletion and increased oxygen diffusion in the EB-PBF fabricated specimen were affected by the coarse grains and formation of vacancies or voids along the grain orientation. Kang et al [26] studied the effect of solution aging and hot isostatic pressing (HIP) on the microstructure and high-temperature oxidation (900, 1000 • C) behavior of Inconel 718 alloy fabricated via the selective laser melting (SLM) method. The results show that, after HIP treatment, the density of sample becomes higher and microstructural differences at the grain boundaries happen, resulting in the improvement of the oxidation resistance of the sample.…”

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confidence: 99%

Hot Corrosion and Mechanical Performance of Repaired Inconel 718 Components via Laser Additive Manufacturing

Zhang

Zhuang

et al. 2020

Materials

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Hot corrosion is one of the crucial failure modes of Ni-based superalloy components operating at high temperatures, which inevitably affects the subsequent mechanical properties of the alloys. In this research, damaged Inconel 718 alloy components with a pre-made trapezoid groove are repaired using laser additive manufacturing technique, and the change mechanisms of the microstructure and tensile properties of the repaired Inconel 718 alloy due to the hot corrosion in the salt mixture of 87.5 wt.% Na2SO4 + 5 wt.% NaCl + 7.5 wt.% NaNO3 at 650 °C for different durations are investigated. The results show that oxidation and Cr-depletion occur on the repaired components due to the hot corrosion, and the corrosion products are mainly composed of Cr2O3, Fe3O4, and Ni3S2. The tensile strength and elongation of the as-repaired specimens are 736.6 MPa and 12.5%, respectively. After being hot corroded for 50 h, the tensile strength increases to 1022.9 MPa and elongation decreases to 1.7%. However, after being hot corroded for 150 h, both tensile strength and elongation of the repaired specimens drop to 955.8 MPa and 1.2%, respectively. The mechanical performance alteration is highly related to thermal effects instead of the molten salt attack.

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“…During high temperature oxidation of alloys, the relative diffusion rate of metal elements depends on several factors, including the Gibbs free energy of formation of the oxide, kinetics, and microstructure (grain size and crystal defects) [ 57 , 58 ]. Although, according to the thermodynamics data, the Gibbs free energy of the formation of Al 2 O 3 (ΔG Θ = −935.12 kJ/mol) is the most negative, comparing with that of TiO 2 (ΔG Θ = −764.35 kJ/mol) and Cr 2 O 3 (ΔG Θ = −575.45 kJ/mol) [ 59 ], a continuous Al 2 O 3 layer could not form due to the content of Al being lower than the critical concentration required to form a continuous Al 2 O 3 layer [ 60 ] in the SHT specimen.…”

Section: Resultsmentioning

confidence: 99%

The Effects of Grain Size and Twins Density on High Temperature Oxidation Behavior of Nickel-Based Superalloy GH738

Luo

Yang

2020

Materials

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In the present study, surface treatment techniques such as room temperature machining (RTM) and low temperature burnishing (LTB) processing have been used to improve the microstructure of GH738 superalloy. Nano-grains and nano-twins are obtained on the top surface of RTM and LTB specimens. It is found that although the grain size of RTM and LTB specimens is almost the same, different types of nano-twins have been produced. Moreover, the effect of RTM and LTB processing on high temperature oxidation behavior of nickel-based superalloy GH738 at 700 °C is investigated. The result shows that LTB specimen has the best high temperature oxidation resistance owing to the formation of nano-grains and higher twins density, which induce to form a continuous protective Al2O3 layer at the interface between outer oxide layer and matrix. It is observed that this layer inhibits the inward diffusion of O and outward diffusion of Ti and significantly improves oxidation resistance of LTB specimen. Furthermore, the effects of nano-grains and crystal defects on the diffusion mechanism of elements are clarified during the high temperature oxidation test.

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Effect of post-treatment on the microstructure and high-temperature oxidation behaviour of additively manufactured inconel 718 alloy

Cited by 86 publications

References 31 publications

Superior Temperature-Dependent Mechanical Properties and Deformation Behavior of Equiatomic CoCrFeMnNi High-Entropy Alloy Additively Manufactured by Selective Laser Melting

Superior Temperature-Dependent Mechanical Properties and Deformation Behavior of Equiatomic CoCrFeMnNi High-Entropy Alloy Additively Manufactured by Selective Laser Melting

Hot Corrosion and Mechanical Performance of Repaired Inconel 718 Components via Laser Additive Manufacturing

The Effects of Grain Size and Twins Density on High Temperature Oxidation Behavior of Nickel-Based Superalloy GH738

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