Electromagnetic Mold Research Articles

Analysis of Flow Pattern and Bubble Behavior in Slab Continuous Casting with Mold Electromagnetic Stirring

The electromagnetic stirring (EMS) and argon blowing are the widely recognized and extensively employed technologies to control the flow pattern in slab continuous casting, and their interaction is directly linked to the final product. To investigate the flow pattern, bubble characteristics under mold EMS and argon blowing, a mathematical model coupling the electromagnetic field, two‐phase flow is constructed. The population balance model (PBM) under the Eulerian frame is applied to describe the bubbles breakage and coalescence. The results show that the flow regime under the interaction of argon blowing and EMS transfers from bubble ascending flow to intermediate flow to horizontal recirculation flow as EMS current increases, and the large argon flow rate could suppress the formation of horizontal recirculation flow. Meanwhile, EMS can promote the coalescence of bubbles, with the increasing EMS current, the bubble numbers decrease first and then increase, and the bubble mean diameter increases first and then decreases. For obtaining the horizontal recirculation flow, the suitable argon flow rate and EMS current should be matched suitably.

Analysis of Transient Flow and Inclusion Transport in Vertical-Bending Slab Continuous Caster with Mold Electromagnetic Stirring

Analysis of Transient Flow and Inclusion Transport in Vertical-Bending Slab Continuous Caster with Mold Electromagnetic Stirring

Modeling and investigation of combined processes of casting, rolling, and extrusion to produce electrical wire from alloys Al–Zr system

The results of modeling and research of casting, rolling, and extrusion processes for producing wire from Al–Zr system alloys and determining its physical and mechanical properties have been presented. When implementing combined processes for processing aluminum alloys, the number of operations is significantly reduced, productivity and yield are increased.As a result of the conducted research, the influence of alloy preparation modes and their chemical composition on the physical, mechanical and electrical properties of longish semifinished products from Al–Zr system alloys obtained by combined rolling-extrusion (CRE) and ingotless rolling-extrusion (IRE) methods were investigated.The simulation of the CRE process for one of these alloys of the system was carried out in the DEFORM 3D software package using data on its rheological properties obtained by the hot torsion method. Based on the modeling results, the optimal modes for conducting experimental studies were selected.The features of metal forming were experimentally studied, the temperature-velocity and technological parameters of combined processing were found, as well as the properties of cast billets, including those obtained using an electromagnetic mold (EMM). The results of experimental studies of the CRE and IRE processes suggest that it is possible to obtain longish deformed semifinished products from alloys Al–Zr system with a level of physical, mechanical and electrical properties that meet international standards.At all technological stages, including drawing, the structure of the metal was studied, and data on the physical and mechanical properties of hot-extruded rods and wire in cold-deformed and annealed states was obtained.The heat resistance of wire made from the investigated alloys was studied and it was found that after testing at a temperature of 280 °C and a holding time of 1 h, it satisfies the requirements of the AT3 type standard with a maximum permissible long-term operating temperature of 210 °C.Recommendations are given for industrial implementation; alloys containing 0.15–0.20% zirconium and 0.10–0.15% iron are recommended for the manufacture of AT1 type wire without heat treatment, as well as 0.25–0.30% Zr and 0.2–0.25% Fe for AT3 wire type with heat treatment.

Industrial Investigation on Inclusions and Solidification Structure of Steel Continuous Casting Slabs Under Mold Electromagnetic Stirring

Industrial Investigation on Inclusions and Solidification Structure of Steel Continuous Casting Slabs Under Mold Electromagnetic Stirring

A Study on Solidification Behavior of a Large Round Bloom Affected by Swirling Flow Submerged Entry Nozzle Combined with Mold Electromagnetic Stirring

A Study on Solidification Behavior of a Large Round Bloom Affected by Swirling Flow Submerged Entry Nozzle Combined with Mold Electromagnetic Stirring

Evaluation of Mold Electromagnetic Stirring in Slab Continuous Casting Based on the Steel/Slag Interface Behavior

Evaluation of Mold Electromagnetic Stirring in Slab Continuous Casting Based on the Steel/Slag Interface Behavior

Multiphase Solidification Modeling of Solidification Structure Evolution and Macrosegregation of Round Bloom Continuous Casting Process with Mold Electromagnetic Stirring and Final Electromagnetic Stirring

Based on Eulerian–Eulerian method, a 3D/2D multiphase solidification model, which takes into consideration the heat transfer and fluid flow with grains nucleation and crystal growth, is developed to predict the macrostructure evolution and macrosegregation in continuously cast round bloom. The results show that the mold electromagnetic stirring (M‐EMS) can accelerate superheat dissipation and promote grain nucleation, but the horizontal swirl induced by M‐EMS has a strong washing effect on the solidification front and leads to subsurface negative segregation. When the M‐EMS current intensity increases from 200 to 300 A, the subsurface negative segregation ratio decreases from 0.935 to 0.875. The final electromagnetic stirring (F‐EMS) not only improves the center segregation, but also leads to the formation of negative segregation zone near the round bloom center due to the enhancement of solute washing induced by F‐EMS. As the F‐EMS current intensity increases from 150 to 300 A, the center segregation ratio decreases from 1.148 to 1.075, and the negative segregation ratio near the strand center decreases from 0.985 to 0.977. Another phenomenon is found that the nucleation of equiaxed grain ahead of columnar tips restrains the solute diffusion and leads to a local macrosegregation in columnar‐to‐equiaxed transition zone.

The Effect of Casting Technique and Severe Straining on the Microstructure, Electrical Conductivity, Mechanical Properties and Thermal Stability of the Al-1.7 wt.% Fe Alloy.

This paper features the changes in microstructure and properties of an Al-Fe alloy produced by casting with different solidification rates followed by severe plastic deformation and rolling. Particularly, different states of the as-cast Al-1.7 wt.% Fe alloy, obtained by conventional casting into a graphite mold (CC) and continuous casting into an electromagnetic mold (EMC), as well as after equal-channel angular pressing and subsequent cold rolling, were studied. Due to crystallization during casting into a graphite mold, particles of the Al6Fe phase are predominantly formed in the cast alloy, while casting into an electromagnetic mold leads to the formation of a mixture of particles, predominantly of the Al2Fe phase. The implementation of the two-stage processing by equal-channel angular pressing and cold rolling through the subsequent development of the ultrafine-grained structures ensured the achievement of the tensile strength and electrical conductivity of 257 MPa and 53.3% IACS in the CC alloy and 298 MPa and 51.3% IACS in the EMC alloy, respectively. Additional cold rolling led to a further reduction in grain size and refinement of particles in the second phase, making it possible to maintain a high level of strength after annealing at 230 °C for 1 h. The combination of high mechanical strength, electrical conductivity, and thermal stability can make these Al-Fe alloys a promising conductor material in addition to the commercial Al-Mg-Si and Al-Zr systems, depending on the evaluation of engineering cost and efficiency in industrial production.

Effect of Mold Electromagnetic Stirring on Metallurgical Behavior in Ultrahigh Speed Continuous Casting Billet Mold

A three‐dimensional model of fluid flow, heat transfer, solidification, and inclusion motion in billet mold at ultrahigh casting speed under electromagnetic field is developed. The low Reynolds number k–ε model coupled with electromagnetic model and Lagrangian discrete phase model is used to investigate the flow field, temperature field, solidification, and inclusions transport under different current intensities. The results show that mold electromagnetic stirring (M‐EMS) significantly alters the flow pattern of molten steel. The impact depth of the molten steel decreases as the stirring current intensity increases, and the horizontal swirl intensities of the molten steel increase with the stirring current intensity. As the current intensity increases from 500 to 700 A, the impact depth decreases from 0.637 to 0.575 m and the maximum tangential velocity increases from 0.477 to 0.898 m s−1. When the stirring current is intense, the flow of molten steel near the mold exit is reversed, and the molten steel flows asymmetrically and unsteadily. The M‐EMS effectively improves the transverse heat transfer of the molten steel in the mold, contributing to the dissipation of the molten steel superheat and the growth of the solidified shell. In addition, the removal ratio of the inclusions is improved significantly.

Combined rolling-extrusion of rods from alloy Al-0.5 REM using billet after electromagnetic mold

Combined rolling-extrusion of rods from alloy Al-0.5 REM using billet after electromagnetic mold

Effect of Nozzle Position on Fluid Flow and Solidification in a Billet Curved Mould using Mould Electromagnetic Stirring

Owing to the smaller cross‐sectional size of the billet, the effect of the position of the submerged entry nozzle (SEN) on the fluid flow in a curved mold is more prominent. The transient fluid flow, heat transfer, and solidification behavior at different nozzle positions and mold electromagnetic stirring (M‐EMS) are investigated using a 3D transient mathematical model. The symmetry index, S, is introduced to quantitatively evaluate the symmetry of the flow field. When the SEN is offset to the outer curve, S is the highest, the flow field mixing is the best, and the liquid level fluctuation is minimal. When the SEN is offset to the inner curve, S is the lowest, and the washing of the solidified shell on the inner curve side is more significant, causing the solidified shell thickness on the inner curve to be thinner, which can easily cause steel breakout accidents. The M‐EMS can improve the uneven flow field caused by the nozzle position. In actual production, the SEN can be appropriately offset to the outer curve, and the application of M‐EMS can improve the flow field distribution of molten steel.

Behavior of Mold Electromagnetic Stirring for Round Bloom Castings and Its Eccentric Stirring Problem.

In this paper, a mold electromagnetic stirring (M-EMS) model was established to investigate the behavior of M-EMS for round bloom castings under different conditions, and an electromagnetic-flow-heat transfer-solidification coupling model was established to explore the problem of eccentric stirring for various formats of round blooms. The results show that the magnetic flux density decreased with the increase in the current frequency, but the electromagnetic torque increases first and then decreases with it, and the same structure of M-EMS for round blooms has the same optimal current frequency at any current intensity. The electromagnetic torque and electromagnetic force both increase as a quadratic function of the current intensity, and the electromagnetic torque, which drives the steel flow, can directly characterize the real M-EMS performance. The mold copper tube has a significant magnetic shielding effect on M-EMS, the stirring intensity decreases rapidly as the tube thickness increases, and the optimal stirring frequency decreases as well. In fact, the deviation between the stirrer center and the geometric center of the strand can result in the eccentric stirring phenomenon. When blooms with a section size of Φ350 mm are produced by Φ650 mm SMS-Concast casting machine, the upper region of the inner arc side and the lower region of the outer arc side are subject to a stronger washing effect, which makes the temperature of the inner and outer arcs show alternating differences. The jet flow from the five-port nozzle can suppress the difference in initial solidification symmetry between the inner and outer arcs of round blooms caused by eccentric stirring. This paper reveals the magnetic shielding effect of the mold copper tube and the magnetic field loss of the air between the stirrer and the inner and outer arcs of the copper, which lead to the stirring intensity and the eccentric stirring phenomenon.

Measurement and Calculation of Magnetic Flux Density During Mold Electromagnetic Stirring on a Continuous Casting Bloom Mold

Measurement and Calculation of Magnetic Flux Density During Mold Electromagnetic Stirring on a Continuous Casting Bloom Mold

Effect of Mold Electromagnetic Stirring on the Flow and Solidification of Φ 800 mm Round Blooms

Knowing the effect of electromagnetic force on fluid flow and solidification within the molds of large-size round blooms is of paramount importance to minimize internal and external defects. In this regard, a three-dimensional coupling model is established, containing magnetohydrodynamics, fluid flow, and heat transfer within the mold, and a new approach for the uniformity of the initial shell is presented. Meanwhile, the effect of stirring parameters on fluid flow and solidification is discussed. The results show that M-EMS can significantly change the temperature and velocity distribution within the mold. These changes can stabilize the level fluctuations and make the initial shell uniform. The maximum industrial height fluctuation was reduced from 1.9 mm to 1.3 mm when the stirring intensity was 375 A/3 Hz. The stirring intensity of M-EMS is relatively ideal.

Production of aluminum alloy onboard wire with a high content of rare-earth metals produced using electromagnetic crystallization

The Scientific and Production Center for Magnetic Hydrodynamics Ltd has developed an innovative technology for casting long ingots of small diameter (8–12 mm) into an electromagnetic mold (EMM) and manufacturing thin wire (0.5 mm in diameter) from them for onboard wires from 01417 alloy. Crystallization of liquid metal occurs under the influence of electromagnetic forces in an electromagnetic mold with direct supply of coolant to the ingot, due to which cooling rates are achieved that ensure the dispersion of the eutectic phases of rare earth metal aluminides, similarly to how it takes place during the crystallization of granules (~1.103...1.104 K/s). It has been established that the determining parameters in casting ingots are the power supplied to the inductor and the level of the melt above the crystallization front. For the casting to reach a steady state (the process of stabilizing the diameter of the ingot after the start of casting), it is necessary to regulate the melt level for some time. The surface quality of the ingot depends on ensuring stability of the current in the inductor during casting. Fluctuations in the current in the inductor lead to changes in the ingot`s diameter. Casting speed and metal temperature have a great influence on the structure of ingots. In contrast to the method of producing granulated wire with a thin (less than 1 mm) cross-section, which turned out to be problematic due to numerous breaks during drawing associated with the presence of oxide and foreign inclusions, the casting technology in the electromagnetic mold does not require preliminary metal filtration, since oxide and solid non-metallic inclusions are intensively squeezed out by electromagnetic forces onto the ingot`s surface. It has been established that hot deformation of a billet cast in the EMM at the Conform facility provides higher strength characteristics of the wire from the 01417 alloy after drawing compared to the cast annealed billet. Pressing provided an increase in the yield strength and relative elongation of the 01417 alloy by 2 and 2.5 times, respectively, compared with the cast state. As a result, the billet was obtained with high technological plasticity for further drawing. Electron microscopic studies of the wire have been carried out, which have shown that dispersed REM aluminides are rather uniformly distributed over the cross section of the wire with a diameter of 0.5 mm. Determination of the particle size of aluminides at ×50000 magnification showed that their size is ~96–214 nm. Wire from 01417 alloy is used by JSC “Special Design Bureau of the Cable Industry” (JSC “OKB KP”) for the manufacture of conductive cores of installation wires, providing a significant reduction in their weight.

Experimental and Analytical Assessment of the Power Parameters of the Combined Rolling-Extruding Process Using a Round Billet from Alloy 01417 Obtained Using an Electromagnetic Mold

Analytical and experimental studies have been carried out, which made it possible to propose new technological modes of combined rolling-extruding for the production of rods from alloy 01417 for the further drawing of wire for electrical purposes. The force parameters on the rolls and the die are calculated when extruding a rod with a diameter of 5 mm on the laboratory unit CRE-200 and the industrial unit CRE-400. The obtained values of the forces on the rolls and the die do not exceed the permissible values of the power load of the units. Therefore the selected parameters are suitable for conducting experiments on the manufacture of prototypes of rods. To verify the conclusions made, experimental studies were carried out on the CRE-200 unit at a temperature of 320 oC and a drawing coefficient μ = 12.1. The results of experimental studies in comparison with the calculated data showed that the deviation of the calculated data does not exceed 15%.

Investigation structure and properties of wire from the alloy of AL-REM system obtained with the application of casting in the electromagnetic mold, combined rolling-extruding, and drawing

The paper presents the results of studies of the structure and properties of a wire with a diameter of 0.5 mm from an alloy of the Al-REM system with a rare-earth metal content of 7–9%. Wire obtained as a result of the implementation of the technology of its manufacture using the methods of casting into an electromagnetic mold (EMM), continuous extruding, and drawing. The rheological properties of the metal of continuously cast round billets from the experimental alloy obtained using an electromagnetic mold are determined. The modeling and analytical assessment of the possibility of carrying out the process of combined rolling-extruding (CRE) of such billets in a closed box-type roll groove of a continuous extruding unit are carried out. The features of metal shaping have been studied. The temperature-speed and technological parameters were found at which the CRE process can be carried out in a stable mode of operation. Data have been obtained for the forces acting on the die and rolls during rolling-extruding. The results of experimental studies of the process of obtaining longish deformed semi-finished products from an experimental alloy on the laboratory unit CRE-200 and the pilot plant unit CRE-400 are presented. The structure of the metal has been studied; data on the ultimate tensile strength, yield strength, relative elongation, and electrical resistance of hot-extruded rods and wires in cold-worked and annealed states have been obtained. It was found that the proposed processing modes make it possible to obtain by the method of combined rolling-extruding rods with a diameter of 9 mm in industrial conditions from longish billets with a diameter of 18 mm, cast by means of EMM. Wire in a cold-deformed and annealed state with a diameter of 0.5 obtained by drawing from the rods with a diameter of 9 mm from an experimental alloy of the Al-REM system containing 7–9% rare-earth metals with the required physical and mechanical properties.

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

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 columnar‐to‐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.

Effect of Mold Electromagnetic Stirring on the Gear Steel Solidification Behavior of Its Large-sized Round Casting

Effect of Mold Electromagnetic Stirring on the Gear Steel Solidification Behavior of Its Large-sized Round Casting

Behavior of non-conducting particles in molten aluminium cast into electromagnetic molds

Behavior of non-conducting particles in molten aluminium cast into electromagnetic molds