Effect of the Gap Between Copper Mold and Solidified Shell on the Fluid Flow in the Continuous Casting Strand with Mold Electromagnetic Stirring

Zhang

Yang

et al. 2021

steel research int.

Self Cite

The solidification structure and macrosegregation are investigated in different current intensities of mold electromagnetic stirring (M-EMS) and final electromagnetic stirring (F-EMS) by a series of industrial trials during the 20CrMnTi bloom continuous casting (CC) process. With the current intensity of M-EMS increasing from 100 to 390 A, the deflection angle of columnar dendrites increases from 25.0 to 32.49 deg. With the current intensity of M-EMS increasing from 0 to 390 A, the equiaxed crystal ratio increases from 20.4% to 25.7% and center porosity varies little. With the increasing current intensity of M-EMS, the negative segregation in the subsurface and positive segregation in the columnarto-equiaxed transition (CET) zone deteriorate gradually. The M-EMS has little effect on the center-positive segregation, and the center-positive segregation is maintained at 1.37-1.40. With the current intensity of F-EMS increasing from 0 to 500 A, the equiaxed crystal ratio is within 25.3-25.8%, and the large center porosities disappear instead of numerous fine spots in the equiaxed zone. The degree of center-positive segregation decreases from 1.48 to 1.30. For the CC process, to obtain a better internal quality of 20CrMnTi bloom, the optimal current intensities of M-EMS and F-EMS are 0 and 500 A, respectively.

Section: The Deflection Angle Of Columnar Dendrites On the Cross Section Of 20crmnti Bloom Under Different Current Intensities Ofmentioning

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effect of Mold Electromagnetic Stirring and Final Electromagnetic Stirring on the Solidification Structure and Macrosegregation in Bloom Continuous Casting

Zhang

Yang

et al. 2021

steel research int.

Self Cite

“…The transient external magnetic field was generated from the alternating current. The magnetic flux density and the current distribution were solved in a transient solver [39,40]. The following three equations were computed in the solver:…”

Section: Electromagnetic Stirring Forcementioning

confidence: 99%

Combined Effects of EMBr and SEMS on Melt Flow and Solidification in a Thin Slab Continuous Caster

Liu

2021

Metals

Electromagnetic fields have emerged as powerful tools for addressing current problems in thin slab continuous casting processes in the iron and steel industry. Substantial studies have been undertaken on the fundamental effects of electromagnetic brakes (EMBr) and strand electromagnetic stirring (SEMS). However, little attention has been focused on melt flow and solidification in a thin slab continuous caster with the simultaneous application of an EMBr and SEMS. The present study aimed to predict transient fields in the caster using a large eddy simulation and an enthalpy-porosity method. The electric potential method was applied in the braking process, and the conductivity change with solidification was considered. The suppressive effect on the intensity of the nozzle jet, the balance effect on the mold flow, and a dispersion effect could be observed. The dispersion effect was a novel finding and was beneficial to a flatter nozzle jet. In contrast, SEMS caused a highly turbulent flow in the strand. A large vortex could be observed in the casting direction. The solidified shell became more uniform, and the solidification rate became obviously slower. These findings supported the view that a high-quality thin slab can be produced by the application of an EMBr and SEMS.

“…The radiation boundary condition was set on the top of the ingot; the heat flux was calculated by Equation ( 8). [23,24]…”

Section: Boundary Conditionsmentioning

confidence: 99%

Simulation of Solidification Structure During Vacuum Arc Remelting Using Cellular Automaton−Finite Element Method

Zhang

et al. 2021

steel research int.

Self Cite

Vacuum arc remelting (VAR) is a secondary melting process for production of metal ingots. [1] In the vacuum condition, the alloy ingot as an electrode was melted by the electric arc and then molten drops fell into the mold. The VAR process was extensively utilized to improve the cleanliness, chemical homogeneity, and mechanical property of metal ingots. [2,3] However, improper melting parameters may result in metallurgical defects, such as macrosegregation, porosities, and beta flecks. [4][5][6] Due to the high temperature of the smelting process, the experimental study was under restriction. The modeling study of the VAR process was used to obtain the optimal parameters for improving the quality of the ingot.Kondrashov et al. [7] developed a simple heat model of the VAR process neglecting the magnetohydrodynamic phenomena in the molten pool. The depth of the molten pool was predicted under different current intensities. Delzant et al. [1] established two models to calculate the thermal radiation of the ingot top during the VAR process. In the crude approach, only the radiative heat transfer between the ingot and the electrode tip was considered. In the detailed approach, all radiative exchanges between the ingot, electrode, and crucible wall were taken into account. Results of the detailed radiation model revealed that the radiative heat transfer of the ingot top was heavily dependent on the arc gap length and the electrode radius. Patel et al. [8] investigated the effect of processing parameters on molten pool profile, flow field, and segregation using a 2D mathematical VAR model. The molten pool profile was significantly affected by the magnetic field. The flow and overall segregation tendency increased with the increase in the magnetic field. Zagrebelnyy et al. [9] established a numerical model to study the segregation of the ingot during the VAR process. The strong flow field was induced by the high arc power resulting in severe macrosegregation. When the arc power was low, the flow was dominated by weaker buoyancy force, and less segregation was formed. Kou et al. [10] calculated the temperature field, fluid flow, and solidification structure of the Ti─6Al─4 V alloy ingot during the VAR process. When the heat radiation was considered, simulated columnar grains on the ingot top agreed well with the experimental results. Chapelle et al. [11] investigated the deformation of the free surface in the VAR process using CFD-based simulations. Two stirring modes were applied in the simulation. In the case of unidirectional stirring, the free surface was a concave dome shape. In the case of alternated stirring, periodic fluctuations of the liquid metal level were generated. Kermanpur et al. [12] established a multiscale