Effect Of Electromagnetic Stirring Research Articles

Study on the synergistic effect of electromagnetic stirring and mechanical reduction on the improvement of the internal homogeneity of high-carbon steel billet

The synergistic effect of electromagnetic stirring (EMS) and mechanical reduction on the improvement of the internal homogeneity has been studied during the continuous casting of high-carbon steel billet. Plant trials were conducted with different parameters both for mold electromagnetic stirring (M-EMS) and final electromagnetic stirring (F-EMS), at the same casting condition and with a unified mechanical reduction process. As the stirring intensity of EMS increases, both the initiation and termination of columnar to equiaxed transition occur at an earlier timing. The results also indicate that, EMS could result in a decline trend for the compactness of the casting billet to a certain extent, especially in the pure equiaxed crystal zone at the core part of the billet. Under the proper intensity setting of M-EMS and F-EMS, the crack susceptibility of the high-carbon steel billet was markedly decreased by enlarging the mixed crystal zone, which is not arrayed with distinct directionality while featured with a relatively high compactness. The effect of EMS on the solidification behavior, and therefore on the crack susceptibility of the high-carbon steel billet was further explained with the numerical simulation. Consequently, a superior inner quality of high-carbon steel billet was successfully achieved with the effective synergy of EMS and mechanical reduction.

Numerical investigation on effect of electromagnetic stirring on macrosegregation in continuously cast round bloom via three-phase solidification model

Based on our previously proposed three-phase solidification model, a comprehensive analysis on the impact of the only electromagnetic stirring (EMS) and combined EMS on the microscopic structure evolution and solute segregation behavior in a 500 mm diameter 42CrMo steel of continuously cast round bloom. The results indicate that M-EMS has a notable impact on expediting the dissipation of superheat, enhancing the initiation of grain formation, and enlarging the equiaxed region. The percentage of equiaxed grains increased from 59.26 to 63.37% with the increment in current intensities of M-EMS from 250 to 350 A. However, higher M-EMS current intensities were found to enhance local positive segregation in the transition zone between columnar and equiaxed grains. The impact of M-EMS on improving center positive segregation was minimal, as the ratio of center positive segregation remained consistently around 1.17. Furthermore, the implementation of F-EMS demonstrated its effectiveness in reducing center positive segregation. The ratio of center positive segregation decreased from 1.14 to 1.10, when the current intensity increases from 150 to 250 A. However, it should be noted that F-EMS alone did not contribute to the expansion of the equiaxed zone. On the other hand, when M-EMS was combined with F-EMS (referred to as combined EMS), it showed potential in mitigating center segregation during continuous casting round blooms. The benefits observed with M-EMS in terms of promoting grain nucleation and expanding the equiaxed grain zone were also evident in this combined EMS process. Furthermore, a notable enhancement in the equiaxed grain ratio up to 60.13% was observed combined EMS models were simultaneously employed during continuous casting of round blooms. And, there was a reduction in center segregation ratio for round blooms to as low as 1.09.

The effect of electromagnetic stirring on processes of alloy crystallization and the macro- and microstructure of continuously cast billets for production of pipes which are resistant to hydrogen sulfide

The effect of electromagnetic stirring on processes of alloy crystallization and the macro- and microstructure of continuously cast billets for production of pipes which are resistant to hydrogen sulfide

Effect of electromagnetic stirring on the transient flow, solidification and inclusion movements in the continuous casting slab mold

PurposeThe purpose of this study is to explore how a time-varying electromagnetic stirring (EMS) affects the fluid flow and solidification behavior in a slab caster continuous casting mold. Further, the study of inclusion movements in the mold is carried out under the effect of a time-varying electromagnetic field.Design/methodology/approachA three-dimensional coupled numerical model of solidification and magnetohydrodynamics has been developed for slab caster mold to investigate the inclusions transport by discrete phase model with the use of user-defined functions. Enthalpy porosity and the Lagrangian approach are applied to analyze the behavior of solidification and inclusion.FindingsThe study shows that the magnetic field density distribution has a radial symmetry in relation to the stirrer’s center. As the EMS current intensity increases, the strength of the lower recirculation zone gradually decreases and nearly disappears at higher intensities. Additionally, the area of localized remelting zone expands in the solidification front with rising current intensity. The morphology of inclusions and EMS current intensity have a significant impact on the behavior and movement of inclusions within the molten steel.Practical implicationsBy using the model, one can optimize the EMS parameter to enhance the quality of steel casting through the elimination of impurities and by improving the microstructure of cast that mainly depend on solidification and flow patterns of molten steel.Originality/valueUntil now, the use of time-varying EMS in the slab caster mold to study solidification and inclusion behavior has not been explored.

Effects of electromagnetic stirring and subsequent homogenization treatment on the microstructure and mechanical properties of Al70Zn10Mg10Cu5Si5 multi-component alloy

Coarse structure and composition segregation inevitably occurred in light-weight multi-component alloys that manufactured by traditional methods due to the high concentration of solute elements. This work proposes a novel idea to address this challenge by using a combination of electromagnetic stirring and homogenization treatment. The optimum ultimate compressive strength and compressive yield strength were 497 MPa and 432 MPa, which were 12.7% and 14.3% higher than those without electromagnetic stirring, respectively. The electromagnetic force increases the number of nuclei and the equiaxed crystal rate by breaking the primary Mg2Si dendrites and shedding the fine grains on the surface of the mold, so as to achieve the purpose of grain refinement. Furthermore, electromagnetic stirring with appropriate frequency can greatly increase the solid solubility, aggravate the lattice distortion, and consequently lead to a noticeable diffusion sluggish effect, resulting in fine and uniform dispersion of the precipitated MgZn2 phase during homogenization. Finally, a strengthening model was established, and the estimated values were highly consistent with the experimental data, with an error ranging within 5%. This study elaborated the microstructure evolution mechanism, offering guidance to fabricate light-weight multi-component alloys with large-size and excellent mechanical properties.

Effect of Electromagnetic Stirring on Shape of β-Al<sub>9</sub>Fe<sub>2</sub>Si<sub>2</sub> Intermetallic Compounds Formed During Solidification of Al–Si–Fe Alloys

A rotating magnetic field was applied during the solidification of Al–Si–Fe alloys (Si = 5 mass% or 10 mass% and Fe = 0.5 mass% or 1 mass%) and the effect of electromagnetic stirring on the area and shape of the intermetallic compounds was studied. The phases formed during solidification of the alloys were not influenced by electromagnetic stirring. The alloys consisted of α-Al, Si and intermetallic β-Al9Fe2Si2. At coil current frequencies above 10 Hz, electromagnetic stirring induced fragmentation of dendritic α-Al, giving rise to coarsening of the β-Al9Fe2Si2 present between the fragmented α-Al grains. The application of electromagnetic stirring at coil current frequencies above 80 Hz decreased the aspect ratio of β-Al9Fe2Si2 in Al–10 mass%Si–1 mass%Fe, while no such decrease was identified in Al–5 mass%Si–0.5 mass%Fe, Al–5 mass%Si–1 mass%Fe or Al–10 mass%Si–0.5 mass%Fe. It was found that the shape of the β-Al9Fe2Si2 phase formed under forced flow of the melt depended significantly on the stirring intensity and the solid fraction of the melt at which intermetallic compounds were formed.

Study of the effect of electromagnetic stirring on the quality of melt solidification in continuous casting

Study of the effect of electromagnetic stirring on the quality of melt solidification in continuous casting

Control of Amount of α-Al Phase Particles in near Eutectic Al-Si Alloy by Electromagnetic Stirring

Al-Si alloy is widely used as a casting alloy. The α-Al phase in the semi-solid state has low Si content in the Al-Si alloy. Then by separation of these α-Al phases from semi-solid Al-Si alloy, refining of aluminum can be possible. But, in near eutectic Al-Si alloy, few primary α-Al phases can be crystallized. If the fraction ratio of the α-Al phase can be increased, near eutectic Al-Si alloy can refine, and this method can be used for recycling. In this study, the effect of electromagnetic stirring (EMS) on the microstructure, especially the amount of the α-Al phase particles was investigated. A rotational magnetic field was applied to JIS ADC12 alloy which has near eutectic content during slow cooling from the liquid state to the solid-state, by using a three-phase AC coil. By applying EMS at solidification, the shape of the α-Al phase became particle shape from dendrite shape, and the amount of α-Al phase particles was increased. Moreover, by applying unidirectional intermittent EMS, the volume fraction of α-Al phase particles was decreased with increasing intermittent applying time. In ADC12 alloy, the primary α-Al phases can be crystallized only 10% generally, but it could be obtained over 40% by applying EMS. This means that the semi-solid slurry of near eutectic alloy with over 40% of fraction solid can be obtained by applying EMS.

Effect of Electromagnetic Frequency on the Flow Behavior in Mold during Bloom Casting

Considering solidification, a large eddy simulation (LES) model of two-phase flow was established to simulate the thermal–magnetic flow coupled fields inside a jumbo bloom. The magnetic field was calculated based on Maxwell’s equations, constitutive equations, and Ohm’s law. An enthalpy–porosity technique was used to model the solidification of the steel. The movement of the free surface was described by the volume of fluid (VOF) approach. With the effect of electromagnetic stirring (MEMS), the vortices in the bloom tended to be strip-like; large vortices mostly appeared in the injection zone, while small ones were found near the surface of the bloom. It is newly found that even though the submerged entry nozzle (SEN) is asymmetrical about the bloom, a biased flow can also be found under the effect of MEMS. The reason for this phenomenon is because the magnetic force is asymmetrical and transient. A high frequency will reduce the period of biased flow; however, the frequency should not be too high because it could also intensify meniscus fluctuations and thus entrap slag droplets in the mold. The velocity near the solidification front can also be increased with a higher frequency.

Effect of Electromagnetic Stirring on Inclusions in Continuous Casting Blooms of a Gear Steel

Effect of Electromagnetic Stirring on Inclusions in Continuous Casting Blooms of a Gear Steel

Microstructures and Macrosegregation of Al-Zn-Mg-Cu Alloy Billet Prepared by Uniform Direct Chill Casting.

In this study, large-sized Al–Zn–Mg–Cu alloy billets were prepared by direct chill casting imposed with annular electromagnetic stirring and intercooling; a process named uniform direct chill casting. The effects of uniform direct chill casting on grain size and the alloying element distribution of the billets were investigated and compared with those of the normal direct chill casting method. The results show that the microstructures were refined and the homogeneity of the alloying elements distribution was greatly improved by imposing the annular electromagnetic stirring and intercooling. In uniform direct chill casting, explosive nucleation can be triggered, originating from the mold wall and dendrite fragments for grain refinement. The effects of electromagnetic stirring on macrosegregation are discussed with consideration of the centrifugal force that drives the movement of melt from the central part towards the upper-periphery part, which could suppress the macrosegregation of alloying elements. The refined grain can reduce the permeability of the melt in the mushy zone that can restrain macrosegregation.

Effect of Electromagnetic Stirring on Microstructure and Mechanical Properties of TiB2 Particle-Reinforced Steel

Effect of Electromagnetic Stirring on Microstructure and Mechanical Properties of TiB2 Particle-Reinforced Steel

Theoretical study of influence of electromagnetic stirring on transport phenomena in wire feed laser beam welding

The additional element from the filler wire in the laser beam welding is usually distributed inhomogeneously in the final weld due to the high solidification rate of weld pool. It has been found that the electromagnetic stirring produced by an external oscillating magnetic field can enhance the material mixing in the weld pool to achieve a more uniform element distribution. However, the magnetic field has a highly nonlinear and multicoupled interaction with the weld pool behavior, which makes the quantitative explanation of the physical mechanism difficult. In this study, the effect of electromagnetic stirring on the transport phenomena in the wire feed laser beam welding is investigated by a numerical modeling. A 3D transient multiphysical model considering the magnetohydrodynamics, heat transfer, fluid flow, keyhole dynamics, and element transport is developed. The multiple reflections and the Fresnel absorption of the laser on the keyhole wall are calculated using the ray tracing method. The numerical results show that a Lorentz force produced by the oscillating magnetic field and its induced eddy current gives significant influence on the transport phenomena in the molten pool. The forward and downward flow is enhanced by the electromagnetic stirring, which homogenizes the distribution of the additional elements from a nickel-based filler wire in a steel weld pool. The numerical results show a good agreement with the high-speed images of the molten pool, the fusion line from the optical micrograph, and the element distribution from the energy dispersive x-ray spectroscopy. This work provides a physical base for the electromagnetic-controlled laser beam welding and some guidance for the selection of electromagnetic parameters.

Effect of Electromagnetic Stirring on the Solidification Behavior of High-Magnetic-Induction Grain-Oriented Silicon Steel Continuous Casting Slab

The solidification behaviors of high-magnetic-induction grain-oriented silicon steel slabs have been investigated during experiments in industrial strand electromagnetic stirring (S-EMS). The current intensities of S-EMS were 0, 120, 200, and 350 A, and the frequency was 5 Hz. The ratio of the equiaxed crystal was 14.95%, 15.64%, 45.22%, and 66.96%, respectively. Central porosity cannot be eliminated by increasing the current intensity. The number, size, and ratio of segregation spots were markedly reduced by minimizing the equiaxed crystal zone. Carbon in the 0 and 120 A slabs exhibited a lower degree of macrosegregation compared with the 200 and 350 A slabs. Controlling the cooling rate and increasing the total reduction are the directions to further improve solidification structures, defects, and carbon segregation.

Physical Modeling of Asymmetrical Flow in Slab Continuous Casting Mold due to Submerged Entry Nozzle Clogging with the Effect of Electromagnetic Stirring

Physical Modeling of Asymmetrical Flow in Slab Continuous Casting Mold due to Submerged Entry Nozzle Clogging with the Effect of Electromagnetic Stirring

Improving the microstructure and tensile properties of AZ91 magnesium alloy via electromagnetic stirring

In this study, the effects of electromagnetic stirring on the microstructure and tensile properties of AZ91 magnesium alloy were investigated by XRD, SEM, TEM, EBSD and tensile test. The results show that the yield strength, ultimate tensile strength and elongation increase to 167 MPa, 187 MPa and 7.5%, rising by 35.8%, 43.8% and 114.3% after the electromagnetic stirring, owing to the refinements of α-Mg and β-Mg17Al12 grains, the increased amount of low angle grain boundaries and the formation of a few tensile twins. The grain refinement mainly originates from the increase in nucleation rate. Electromagnetic stirring improves the plasticity of AZ91 alloy with poor ductility, and further increases the application of AZ91 alloy.

Size and Type of Inclusions in Fe–Cr–Co Heat–resistant Steel and Elevated-temperature Strength under the Effect of Electromagnetic Stirring

Size and Type of Inclusions in Fe–Cr–Co Heat–resistant Steel and Elevated-temperature Strength under the Effect of Electromagnetic Stirring

Effect of electromagnetic stirring and solution treatment on microstructure and properties of AZ31 magnesium alloy

AbstractEffect of electromagnetic stirring and solution treatment on the microstructural evolution and mechanical properties of AZ31 alloy are investigated in this study. Results show that the mechanical properties of AZ31 alloy are substantially increased after electromagnetic stirring and solution treatment. The tensile strength and elongation are 178 MPa and 19.6 % for AZ31 alloy prepared by electromagnetic stirring after solution treatment. A large number of twins and low angle boundaries are observed in the specimen after heat treatment, since the compressive stress on ( ) crystal plane become larger during quenching. The dislocation arrays, which produced by slip or climbing of dislocations, join together to form low angle boundaries.

Investigation on laser cladding Ni-base coating assisted by electromagnetic field

Laser cladding Ni-base coatings were prepared on pure iron assisted by an electromagnetic compound field. The microstructure, phase composition, crack and microhardness of the cladding coatings were investigated. Results indicated that laser cladding Ni-base coatings with and without the electromagnetic field was composed of γ-(Fe, Ni), CrB, Cr7C3, Ni3B and Ni2B. The electromagnetic compound field could promote the transformation of γ-(Fe, Ni) to equiaxed crystals. The volume fraction of hard phase CrB can be increased by electromagnetic field. Mechanical scouring effect of electromagnetic stirring makes hard phase Cr7C3 form an independent rod structure. The number of cracks in coatings is decreased under the electromagnetic field. The average microhardness of cladding coatings increased to 923.7 HV0.2. Under the combined action of the electromagnetic stirring and current thermal effect, the temperature gradient in the molten pool had an optimum value. That is, the value of AC current was 1200 A and magnetic flux intensity was 0.2 T.

Mathematical modelling of inclusion motion and entrapment in billet mould with effect of electromagnetic stirring

ABSTRACTIn-mould electromagnetic stirring (M-EMS) is a widely used technique during continuously casting (CC). To investigate the M-EMS effect on the inclusion motion and entrapment in a billet CC mould, a coupling mathematical model was developed. The result indicates that the M-EMS changes molten steel flow pattern and transient inclusion distributions in the mould. Inclusions have a tendency to move close to the mould centre under M-EMS. When the M-EMS is off, the distributions of inclusions in the solidified shell is relatively uniform. When the M-EMS is applied, many inclusions are entrapped near the stirrer mid-plane. Furthermore, distances of captured inclusions below the billet surface become larger. Additionally, the M-EMS has a significant effect on the overall removal fraction of inclusions. At last, detection of inclusions in samples obtained from a plant has been performed. A similar tendency can be found between the predicted and experimental results.