Influence of platform position on stray grain nucleation in Ni-based single-crystal dummy blade clusters

Yang, Zhenyu; Liu, Chenguang; Hu, Songsong; Zheng, Su-jie; Luo, Yushi; Dai, Shen-long

doi:10.1007/s41230-021-1053-3

Cited by 3 publications

(1 citation statement)

References 21 publications

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“…However, no matter which method is adopted, misorientation defects [2][3][4] are almost inevitable. Stray grain (SG) defects are common, particularly around the platforms and shroud regions [5][6][7][8][9] of the turbine blade, and can lead to component invalidation.…”

Section: Introductionmentioning

confidence: 99%

The Stray Grains from Fragments in the Rejoined Platforms of Ni-Based Single-Crystal Superalloy

Huo

Chen

Han

et al. 2023

Metals

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Nickel-based single crystal superalloy is the most important material for blade preparation. However, some solidification defects inevitably occur during the process of preparing single-crystal blades through directional solidification. In this study, in order to study the origin of misorientation defects during solidification, a model with rejoined platforms was designed according to the geometry of single-crystal guide vanes. Electron Back-Scattering Diffraction (EBSD) was used to quantify the orientation deviation of the dendrites and identify the solidification defects in the rejoined platforms. The results showed that stray grain defects appeared in the platforms and their misorientation changed gradually, not abruptly. Combined with the simulation results, it was proposed that the stray grains formed as the result of the dendrites fragment, which was induced by solute enrichment in the mushy zone during solidification. Meanwhile, it was accompanied by a obvious dendritic deformation, which was caused by solidification shrinkage stress. This suggested that the fragmentation was induced by multiple factors, among which, the concave interface shape provided favorable conditions for solute enrichment, and the dynamic variability in the local thermal gradient and fluctuations of the solidification rate might play catalytic roles.

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Section: Introductionmentioning

confidence: 99%

The Stray Grains from Fragments in the Rejoined Platforms of Ni-Based Single-Crystal Superalloy

Huo

Chen

Han

et al. 2023

Metals

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Microscale stray grains formation in single-crystal turbine blades of Ni-based superalloys

Wang,

Liu,

Yang

et al. 2024

Journal of Materials Science & Technology

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Comparative Investigation of the Undercooling Capacity and Single-Crystal Castability of Some Ni-Based Superalloys

Zhao

Xu³

et al. 2022

Crystals

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The undercooling capacity of a superalloy is an essential physical property to determine its single-crystal (SC) castability, because stray grains (SGs) will be formed if the geometrical undercooling established at the platform extremities exceeds the undercooling capacity of the applied alloy. In the present work, both the undercooling capacity of eight Ni-based superalloys and their SC castability were experimentally investigated. The liquidus temperature, the critical temperature for grain nucleation, and hence the undercooling capacities of the investigated alloys were evaluated based on the temperature evolution during the heating and cooling processes. The current experimental study revealed a significant difference in undercooling capacity for the superalloys. In the production of SC blade castings, the tendency to form SG defects was found to be highly related to the alloy’s undercooling capacity. The alloys having a low undercooling capacity of around 10 K were very prone to the formation of SGs. In comparison, the alloys with a moderate undercooling capacity from 20 K to 30 K could be easily cast into SC blades without SGs, exhibiting the best SC castability. Other factors influencing the SG formation were also analyzed. As a result, a criterion for the formation of geometry-related SG defects was proposed, in which the influence of the alloy undercooling capacity, casting geometry, and solidification condition are involved.

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Influence of platform position on stray grain nucleation in Ni-based single-crystal dummy blade clusters

Cited by 3 publications

References 21 publications

The Stray Grains from Fragments in the Rejoined Platforms of Ni-Based Single-Crystal Superalloy

The Stray Grains from Fragments in the Rejoined Platforms of Ni-Based Single-Crystal Superalloy

Microscale stray grains formation in single-crystal turbine blades of Ni-based superalloys

Comparative Investigation of the Undercooling Capacity and Single-Crystal Castability of Some Ni-Based Superalloys

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