Modelling melting and grain destruction phenomena during globular equiaxed solidification

Zhang, Haijie; Wu, Menghuai; Schumacher, Peter; Rodrigues, Christian M. G.; Ludwig, Andreas; Kharicha, Abdellah

doi:10.1016/j.apm.2021.04.024

Cited by 12 publications

(3 citation statements)

References 51 publications

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“…Because the grain remelting was assumed to be governed by diffusion, equation (10) was valid to calculate the remelting speed vRe. In each calculation cell, the equiaxed grains were assumed to follow a lognormal size distribution, equation ( 8) [13]. When the grain diameter was melted to smaller than a critical value e,critical d , the grain would be eliminated from the casting domain, i.e.…”

Section: Table II Formulations For Capillarymentioning

confidence: 99%

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Numerical study on the formation of spurious grains and freckles during the directional solidification of superalloys

Zhang

Liu

et al. 2023

IOP Conf. Ser.: Mater. Sci. Eng.

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Freckles, a significant issue encountered during the directional solidification of superalloys, are recognised by a trail of equiaxed grains parallel to the direction of gravity accompanied by local eutectic enrichment. In the current study, a mixed-columnar-equiaxed multiphase volume-average solidification model was employed to study the formation of freckles in superalloy casting. Fragments produced via flow-driven and capillary-driven fragmentation mechanisms are considered as the source of spurious grains. The transport and the growth/remelting of the fragments are considered. According to the simulation results, some segregation channels develop at the corners of the casting. Flow-driven fragments are produced in/around the segregation channels, whereas capillary-driven fragments are produced at a certain depth of the mushy zone across the entire section of the casting. The fragmentation rate caused by the flow-driven mechanism is several orders of magnitude larger than that caused by the capillary-driven mechanism, i.e. the flow-driven fragmentation mechanism is dominant for the currently investigated sample. After the solidification process, four freckles formed at the casting corners on the shadowed side, whereas it was freckle-free on the bright side.

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Section: Table II Formulations For Capillarymentioning

confidence: 99%

“…The remelting and solidification of the as-formed solid phases (i.e. columnar dendrites and equiaxed grains) were also considered [13]. The main goal of this study was to numerically investigate the formation of spurious grains produced by different fragmentation mechanisms, and hence the onset of freckles.…”

Section: Introductionmentioning

confidence: 99%

Numerical study on the formation of spurious grains and freckles during the directional solidification of superalloys

Zhang

Liu

et al. 2023

IOP Conf. Ser.: Mater. Sci. Eng.

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“…Their findings indicated that equiaxed crystal settlement could result in negative macrosegregation at the bottom of the ingot, while it influenced positive macrosegregation in the upper part of the ingot. Based on the Eulerian approach, Zhang et al [7] used a two-phase model to simulate the solidification of an ingot. In this model, equiaxed crystal nucleation, microstructure evolution, grain/crystal dissociation, precipitation, melt convection, and solute transport were fully considered.…”

mentioning

confidence: 99%

Volume-averaged modeling of multiphase solidification with equiaxed crystal sedimentation in a steel ingot

Zhu,

Cao,

Guan

et al. 2024

China Foundry

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The connecting shaft between the support arm and the base is the main bearing part of hydraulic support equipment for mining. As the equipment size increases, manufacturers raise their expectations for the mechanical properties of connecting shafts. During the casting of connecting shafts, macrosegregation hinders the improvement of mechanical properties [1] . The primary mechanism for macrosegregation is the relative movement between

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Solidification Principle in Large Vertical Steel Casting Under the EMS Effect

Zhang

et al. 2023

Metall Mater Trans B

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The surging demand for large high-quality rotor shafts or similar steel components in heavy industries (energy sector) poses new challenges to steelmakers. Based on the experience of conventional ingot and continuous casting, several new process concepts have been proposed, e.g., vertical continuous casting (VCC), semi-continuous casting (SCC), and segment casting (SC), but none of them are optimally put in operation. The main problems include the control of the as-cast structure and macrosegregation. Electromagnetic stirring (EMS) is necessary to obtain the center equiaxed zone, but EMS-induced multiphase flow can cause severe macrosegregation and uneven distribution of the as-cast structure between equiaxed and columnar. In this study, an advanced mixed columnar-equiaxed solidification model was used to investigate the formation of the as-cast structure and macrosegregation in an example of SCC with a large format (diameter 1 m). The main role of EMS is to create crystal fragments by fragmentation, which is regarded in this work as the only origin of equiaxed grains. The created equiaxed grains are brought by the EMS-induced (primary and secondary) flow and gravity-induced sedimentation to the central/lower part of the casting. The main goal of this study was to understand the solidification principle of SCC. In addition, a numerical parameter study by varying the EMS parameters was also performed to demonstrate the model capability towards the process optimization of SCC.

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Modelling melting and grain destruction phenomena during globular equiaxed solidification

Cited by 12 publications

References 51 publications

Numerical study on the formation of spurious grains and freckles during the directional solidification of superalloys

Numerical study on the formation of spurious grains and freckles during the directional solidification of superalloys

Volume-averaged modeling of multiphase solidification with equiaxed crystal sedimentation in a steel ingot

Solidification Principle in Large Vertical Steel Casting Under the EMS Effect

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