Removal of Non-metallic Inclusions from Nickel Base Superalloys by Electromagnetic Levitation Melting in a Slag

Manjili, Mohsen Hajipour; Halali, Mohammad

doi:10.1007/s11663-017-1137-z

Cited by 17 publications

(5 citation statements)

References 21 publications

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“…A positive effect of higher CaF 2 ‐contents on inclusion removal as described in ref. for a Ni‐base Superalloy could therefore not be confirmed. Higher SiO 2 ‐contents in the slag affect the SiO 2 ‐ration in the non‐metallic inclusions significantly, which is described in detail in ref.…”

Section: Discussionmentioning

confidence: 97%

Effect of the Slag Composition and a Protective Atmosphere on Chemical Reactions and Non‐Metallic Inclusions during Electro‐Slag Remelting of a Hot‐Work Tool Steel

Schneider

Molnar

Gelder

et al. 2018

steel research int.

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The remelting behavior of the hot-work tool steel X37CrMoV5-1 is investigated with several experimental melts on a lab-scale ESR-plant. The investigated parameters comprise a variation of the slag compositions and the use of a protective nitrogen atmosphere. Variations of the slag composition include slags with different contents of CaF 2 , CaO, and Al 2 O 3 as well as a variation of the SiO 2content in the slag. The remelted ingots are forged and analyzed regarding their chemical composition. The distribution and composition of the non-metallic inclusions (NMI) is studied by an automated SEM-EDX method. Additionally, the chemical composition of the slag after remelting is analyzed. The results show clearly an equilibrium reaction between Si and Al in the steel with SiO 2 and Al 2 O 3 in the slag as well as the effect of oxygen in open ESR operation. A protective atmosphere reduces the Si-losses during remelting, but has no major effect on the number or composition of NMI compared to open remelting. The content of NMI, especially the larger ones, is reduced significantly in all remelting experiments. The majority of the NMI are MA-spinel type except for the CaO-free slag, where alumina inclusions prevail. In general, remelting leads to an almost complete removal of sulfides, a reduction of oxisulfides, and a slight increase of oxides.

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Section: Discussionmentioning

confidence: 97%

Effect of the Slag Composition and a Protective Atmosphere on Chemical Reactions and Non‐Metallic Inclusions during Electro‐Slag Remelting of a Hot‐Work Tool Steel

Schneider

Molnar

Gelder

et al. 2018

steel research int.

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“…Nevertheless, none of these techniques can ensure sufficient stirring and turbulence in molten droplets, which limits the removal efficiency of the inclusions. 10) Compared with oxide inclusions, nitride inclusions are more difficult to be removed by the current methods, since nitride inclusions dissolve when the superalloy melt and precipitate again as the temperature decreases in the solidification process of the superalloy. It is found that the dissolution of these inclusions has hardly effect on the removal process.…”

Section: Supergravity-induced Separation Of Oxide and Nitride Inclusimentioning

confidence: 99%

Supergravity-Induced Separation of Oxide and Nitride Inclusions from Inconel 718 Superalloy Melt

et al. 2020

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Herein, a method of supergravity-enhanced separation was used to remove oxide and nitride inclusions from Inconel 718 superalloy melt, with elucidating the inclusion removal behavior by varying the gravity coefficients (G) and separation times (t) used for melt treatment. Under supergravity conditions, inclusions concentrated at the sample top and are almost absent at the sample bottom. Moreover, the inclusion number density and average size showed a gradient distribution along the supergravity direction, and the steepness of this gradient rapidly increased with increasing G and t. The experimentally determined inclusion movement velocities agreed well with those calculated using Stokes's law at G ≤ 210 and t ≤ 10 min. At G = 210 and t = 10 min, the total oxygen and nitrogen contents of the sample decreased from 34.4 to 8.7 ppm and 133.4 to 34.1 ppm, respectively, corresponding to oxide and nitride removal efficiencies of 74.7% and 74.4%, respectively.

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“…Загрязненность образцов неметаллическими включениями оценивали с помощью определения уровня опасности включений по методу Low Inclusion Content (метод D), описанному в стандарте ASTM E 45-97 [19] путем анализа зон шлифа размером 0,71×0,71 мм.…”

Section: материалы и методика исследованияunclassified

“…Это способствует вытеснению неметаллических включений на поверхность металла, что и наблюдалось в процессе плавки. Такого же результата можно добиться и плавкой в индукторе при достаточном для удаления неметаллических включений в шлак времени выдержки расплава в жидком состоянии [19].…”

Section: результаты и их обсуждениеunclassified

Effect of scrap using in charge on the microstructure and properties of ZhS6U nickel-based superalloy. Part 2. Structure analysis and mechanical properties of ZhS6U prepared with scrap

Колтыгин

Баженов

Базлов

et al. 2019

Izv. vysš. učebn. zaved., Čern. metall.

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The second part of the article considers influence of the scrap amount on structure and mechanical properties of ZhS6U-VI nickelbased superalloy. As the use of scrap is associated with the possibility of alloy contamination by nonmetallic inclusions and loss of alloying elements, the influence of scrap on alloy structure and mechanical properties is in great importance. The samples with diameter of 12 mm were melted in a vacuum arc furnace and were casted into a copper mold from the virgin ZhS6U-VI alloy without scrap and from alloys with 50 % and 100 % of scrap. The alloys structures were investigated using optical microscopy on etched metallographic sections that were cut from the samples’ cross-sections. The studies were carried out on the as-cast samples and the samples after solution heat treatment for 4 hours at 1210 °C. The slightly higher nonmetallic inclusions content were observed in the structure of the alloy melted with scrap in comparison with virgin alloy melted without scrap. For the sample that was melted from 100 % of scrap the inclusions secure level is 3 (ASTM E 45-97) with an average size of inclusions of 28.4 ± 0.2 μm. Herewith the presence of single large inclusions with a size of not more than 70 microns was noted. However, it has no effect on the alloy mechanical properties. Mechanical properties after heat treatment (ultimate strength (UTS) = 1090 – 1100 МPа and elongation (El) = 9 – 11 %) were obtained on the samples melted using 50 and 100 % of scrap and fully correspond to the TU1-92-177-91 standard for ZhS6U-VI nickel-base superalloy. During solidification most of the large nonmetallic inclusions are concentrated under casting surface, which makes their machining difficult. Because of that the use of 100 % scrap without its preliminary processing is not recommended. Acceptable results were achieved when the 50 % of scrap was used.

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Removal of Non-metallic Inclusions from Nickel Base Superalloys by Electromagnetic Levitation Melting in a Slag

Cited by 17 publications

References 21 publications

Effect of the Slag Composition and a Protective Atmosphere on Chemical Reactions and Non‐Metallic Inclusions during Electro‐Slag Remelting of a Hot‐Work Tool Steel

Effect of the Slag Composition and a Protective Atmosphere on Chemical Reactions and Non‐Metallic Inclusions during Electro‐Slag Remelting of a Hot‐Work Tool Steel

Supergravity-Induced Separation of Oxide and Nitride Inclusions from Inconel 718 Superalloy Melt

Effect of scrap using in charge on the microstructure and properties of ZhS6U nickel-based superalloy. Part 2. Structure analysis and mechanical properties of ZhS6U prepared with scrap

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