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1 – 3 of 3P. Turewicz, E. Baake and A. Umbrashko
The purpose of this paper is to describe how electromagnetic stirring during continuous casting of ferrous and non‐ferrous metals is applied in order to increase the homogeneity…
Abstract
Purpose
The purpose of this paper is to describe how electromagnetic stirring during continuous casting of ferrous and non‐ferrous metals is applied in order to increase the homogeneity and the material properties by improving the grain refinement in the solidification process. The fluid flow and thermal modeling was performed for studying the metal wire pulling process, where melt is being stirred at the solidification front (SF) by electromagnetic forces. Transient simulation has been carried out in order to investigate the periodical character of the process.
Design/methodology/approach
The numerical analysis was performed in 2D utilizing the rotational symmetry of the problem. First the electromagnetic fields were estimated using FEM and were subsequently exported as source terms in a coupled thermal and flow simulation with FVM.
Findings
The presented numerical model estimated the most suitable position between the stirring coil and the SF to achieve high flow velocities which improve the grain refinement process.
Originality/value
This work enables estimation of the melt solidification in an electromagnetic stirred continuous casting process with oscillating pull velocities.
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Ambrish Maurya and Pradeep Kumar Jha
The purpose of present investigation is to analyze the in-mold electromagnetic stirring (M-EMS) process and the effect of stirrer frequency on fluid flow and solidification in a…
Abstract
Purpose
The purpose of present investigation is to analyze the in-mold electromagnetic stirring (M-EMS) process and the effect of stirrer frequency on fluid flow and solidification in a continuous casting billet caster mold.
Design/methodology/approach
A hybrid approach involving finite element and finite volume method has been used for the study. Finite element model is used to calculate time variable magnetic field, which is further coupled with fluid flow and solidification equations for magneto-hydrodynamic analysis with finite volume model.
Findings
Results show that though superheat given to steel before its entry into the mold is quickly removed, solid shell formation is delayed by the use of M-EMS. Final solid shell thickness, however, is slightly reduced. Increase in frequency is found to increase the magnetic flux density and tangential velocity of liquid steel and decrease in diameter of liquid core.
Practical implications
The work is of great industrial relevance. The model may be used to design industrial setup of in-mold electromagnetic stirrer and process could be analyzed and optimized numerically.
Originality/value
The paper evaluates the influence of M-EMS and its frequency on solidification and flow behavior in the continuous casting mold. The iso-surface temperatures from pouring temperature to liquidus temperature inside the mold have been shown. The findings may be useful for the steelmakers to reduce the defect in continuous casting.
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Ambrish Maurya and Pradeep Kumar Jha
This investigation aims to analyze the steel-flux interface level fluctuation because of electromagnetic stirring and its process parameters in a continuous casting billet mold.
Abstract
Purpose
This investigation aims to analyze the steel-flux interface level fluctuation because of electromagnetic stirring and its process parameters in a continuous casting billet mold.
Design/methodology/approach
An un-coupled numerical model for electromagnetic field generation and a coupled numerical model of electromagnetic field and two-phase fluid flow have been developed. The two-phase fluid flow has been modeled using volume of fluid method, in which externally generated time-varying electromagnetic field is coupled and analyzed using magnetohydrodynamic method. Top surface standing wave stability criteria are used to study the criticality of interface stability.
Findings
Results show that application electromagnetic field for stirring increases the interface level fluctuation, specifically at the mold corners and near the submerged entry nozzle. The increase in current intensity and stirrer width barely affect the interface level. However, interface level fluctuation increases considerably with increase in frequency. Using stability criteria, it is found that at 20 Hz frequency, the ratio of height to wavelength of interface wave increases much above the critical value. The iso-surface of the interface level shows that at 20 Hz frequency, mold flux gets entrapped into the liquid steel.
Practical implications
The model may be used during optimization of in-mold electromagnetic stirrer to avoid mold flux entrapment and control the cast quality.
Originality/value
The study of mold level fluctuation in the presence of in-mold electromagnetic stirrer has rarely been reported. The criticality of stirrer process parameters on level fluctuation has not been yet reported. This study lacks in experimental validation; however, the findings will be much useful for the steelmakers to reduce the casting defects.
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