Solidification in remelting processes

Mitchell, A.

doi:10.1016/j.msea.2005.08.157

Cited by 109 publications

(52 citation statements)

References 3 publications

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“…Due to the clockwise circular flow at the solidification front, the solute-poor (Ni, Cr, and C) metal in the pool displaces the solute-rich metal through washing the mushy region. Furthermore, the solute enrichment increases the metal density and thus promotes the sinking of the liquid metal [16,17]. As a result, the Ni, Cr, and C accumulate at the base of the pool and the concentration increases with increasing distance from the bottom of the ingot.…”

Section: Macrosegregation Of the Esr Ingotmentioning

confidence: 99%

The Structural Evolution and Segregation in a Dual Alloy Ingot Processed by Electroslag Remelting

Liu

Zhang

et al. 2016

Metals

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Abstract:The structural evolution and segregation in a dual alloy made by electroslag remelting (ESR) was investigated by various analytical techniques. The results show that the macrostructure of the ingot consists of two crystallization structures: one is a quite narrow, fine, equiaxed grain region at the edge and the other is a columnar grain region, which plays a leading role. The typical columnar structure shows no discontinuity between the CrMoV, NiCrMoV, and transition zones. The average secondary arm-spacing is coarsened from 35.3 to 49.2 µm and 61.5 µm from the bottom to the top of the ingot. The distinctive features of the structure are attributed to the different cooling conditions during the ESR process. The Ni, Cr, and C contents markedly increase in the transition zone (TZ) and show a slight increase from the bottom to the top and from the surface to the center of the ESR ingot due to the partition ratios, gravity segregation, the thermal buoyancy flow, the solutal buoyancy flow, and the inward Lorentz force. Less dendrite segregation exists in the CrMoV zone and the transition zone due to a stronger cooling rate (11.1 and 4.5 • C/s) and lower Cr and C contents. The precipitation of carbides was observed in the ingot due to a lower solid solubility of the carbon element in the α phase.

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Section: Macrosegregation Of the Esr Ingotmentioning

confidence: 99%

The Structural Evolution and Segregation in a Dual Alloy Ingot Processed by Electroslag Remelting

Liu

Zhang

et al. 2016

Metals

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“…As is well known, the electrode is molten by resistance heating generated in liquid slag pool 3,18) when current transfer through it. The capacity of resistance heating has relationship with current density distribution in liquid slag pool besides the physical properties of slag.…”

Section: Influence Of Slag Height On the Esr Processmentioning

confidence: 99%

“…The depth of molten steel is 1/4 to 1/3 of mould diameter for four electrodes with two sets of bifilar configuration method; however, it is 1/3 to 1/2 of mould diameter for conventional single electrode single phase ESR process. 3,18) Comparing with conventional single electrode single phase ESR process, the depth of molten steel pool is shallower for four electrodes with two sets of bifilar configuration method.…”

Section: Influence Of Slag Height On the Esr Processmentioning

confidence: 99%

“…By adding filling ratio, productivity can be increased; production cost can be decreased, production cycle can be shortened. 3,22) In this part, different filling ratio has been studied. The diameters of electrode are 350 mm, 400 mm and 450 mm and the filling ratio are 0.151, 0.198 and 0.250 according to area, respectively.…”

Section: Impact Of Electrode Diameter On the Esr Processmentioning

confidence: 99%

“…However, mathematical model is a good method, which will help us to choose reasonable parameters. 3,4) Though many mathematical models [5][6][7][8][9][10][11][12][13] have been developed for simulating the process since birth of this technology, which aims to understand the process and analysis impact of various factors on the ingot quality, most models are based on small-scale furnace and single phase with one electrode. The latest literature 14) is still for single electrode electroslag remelting process.…”

Section: Introductionmentioning

confidence: 99%

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Simulation of Multi-electrode ESR Process for Manufacturing Large Ingot

et al. 2012

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Electroslag remelting process will be an important method for manufacturing heavy casing and forging due to its ability to improve the cleanness, macrostructure, microstructure, the distribution and size of non-metallic inclusions. In this paper, a finite element coupling model has been developed based on four electrodes configuration mode for manufacturing large ingot. Maxwell equation, Faraday's law, NavierStokes equation, heat transfer equation has been adopted in the model to analyze the current density, Joule-heat density, magnetic induction intensity and electromagnetic force and fluid flow distribution. The impact of slag depth, electrodes immersion depth and filling ratio on the molten pool depth has been analyzed. Results indicated that four electrodes with two sets of bifilar configuration are better than single phase with one electrode type. The molten pool is shallower for four electrodes than conventional single electrode mode, which is in favor of improving large ingot quality. The larger slag pool depth is the shallower the molten pool is. The depth of molten steel pool increases with the increasing of electrode immersion depth under the same slag depth condition. In addition, increasing filling ratio can reduce the depth of molten steel pool, but the filling ratio should be less than 0.6 according to area for general materials. Comparing to the single electrode mode four electrodes configuration mode is in favor of manufacturing large ingot.

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Solidification Front Tilt Angle Effect on Potential Nucleation Sites for Freckling in the Remelt of Ni‐Base Superalloys

Valdés

Liu

King

et al. 2010

Superalloy 718 and Derivatives

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By considering the mushy layer as a porous media with variable permeability, a Rayleigh number based freckling criterion was developed from the Flemings ratio between the magnitude of the interdendritic flow velocity and the solidification rate. The proposed form includes the effect of the tilt angle by preserving the anisotropic nature of the permeability tensor throughout the derivation and uses Poirier's experimentally determined functional forms for the parallel and perpendicular components. The proposed form of Rayleigh number criterion was found to provide better resolution when evaluated against available experimental data in the literature.Especially, it showed that the nucleation of channels in the mushy layer leading to freckles is equally probable in the proximity of the tips of the dendrites or deeper in the mushy layer, for example at approximately 0.7 liquid fraction and 0.4 liquid fraction respectively, depending on the angle of tilt of the solidification front.

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Solidification in remelting processes

Cited by 109 publications

References 3 publications

The Structural Evolution and Segregation in a Dual Alloy Ingot Processed by Electroslag Remelting

The Structural Evolution and Segregation in a Dual Alloy Ingot Processed by Electroslag Remelting

Simulation of Multi-electrode ESR Process for Manufacturing Large Ingot

Solidification Front Tilt Angle Effect on Potential Nucleation Sites for Freckling in the Remelt of Ni‐Base Superalloys

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