Explore the vast range of titles available.

Electromagnetic brakes (EMBrs) are regularly used in continuous casting to control interface fluctuations in a mould. In the research, to appraise the damping effect of EMBr technique, namely EMBr-ruler technique, the influence of magnetic field intensity on behaviours of melt flow and interface fluctuation in a Compact Strip Production (CSP) thin slab funnel mould are numerically simulated. The numerical results illustrate that the existence of the EMBr-ruler technique is conducive to inhibiting the impact of the ascending circulation on the interface in the CSP funnel mould. With the gradual enhancement of magnetic intensity, the service efficiency of the EMBr-ruler on the fluctuation of two-phase steel/slag interface is enhanced. For instance, by applying a magnetic induction intensity of 0.5 T, the maximum fluctuation height of two-phase steel/slag interface is decreased to 6.4 mm. This can well prevent surface defects, such as slag entrapment.

Centrifugal casting is mostly used to manufacture cylinder liners at present. Electromagnetic fields can realize the function of no pollution and optimize the structure and mechanical properties. On the foundation of centrifugal casting, electromagnetic centrifugal casting adds a magnetic field to generate electromagnetic stirring so that casting defects are controlled. In this article, Al-7Si-4Cu is selected as the simulation object, using Fluent software to set up a model with a rotating speed of 1700 rpm, a magnetic field strength of 0.05 T, a pouring temperature of 750°C, an initial mold temperature of 250°C, and a pouring speed of 0.45 m/s. According to the analysis of the temperature field and flow field, the rule of flowing characteristics of liquid metal and heat transfer effects can be predicted. Furthermore, we evaluate the changes in the approximate area of defects of the outer surface, which has a certain guiding function for the electromagnetic centrifugal casting technology.

In the production of aluminum castings, grain refiners are extensively used to achieve the desired grain refinement. However, the high cost associated with these materials significantly increases the overall expenses of the casting process. As a result, one of the primary goals in foundry operations is to implement more cost-effective methods of grain refinement. This study focuses on the innovative use of low-energy pulsed electromagnetic energy as an alternative approach for grain refinement during the casting of 5356 aluminum alloy. The research conclusively demonstrates the effectiveness of applying electromagnetic energy directly to the molten metal to refine the grain structure. Experimental investigations were carried out in an industrial casting environment, where the influence of electromagnetic energy on the solidification behavior of the 5356 aluminum alloy was systematically analyzed. The findings revealed a significant improvement in grain refinement, with a 16% reduction in grain size observed in the low cooling region of the cast material. Moreover, the application of electromagnetic energy was shown to promote the precipitation of the silicon (Si) phase, further enhancing the microstructural properties of the alloy. These results highlight the potential of using low-energy pulsed electromagnetic technology as a practical and cost-effective solution for grain refinement in aluminum foundry operations. The insights gained from this research may contribute to the development of more efficient casting techniques, ultimately reducing production costs while maintaining or improving the quality of the final product.

This paper reviews the current state of the art in the application of electromagnetic forces to control fluid flow to improve quality in continuous casting of steel slabs. Many product defects are controlled by flow-related phenomena in the mold region, such as slag entrapment due to excessive surface velocity and level fluctuations, meniscus hook defects due to insufficient transport of flow and superheat to the meniscus region, and particle entrapment into the solidification front, which depends on transverse flow across the dendritic interface. Fluid flow also affects heat transfer, solidification, and solute transport, which greatly affect grain structure and internal quality of final steel products. Various electromagnetic systems can affect flow, including static magnetic fields and traveling fields which actively accelerate, slow down, or stir the flow in the mold or strand regions. Optimal electromagnetic effects to control flow depends greatly on the caster geometry and other operating conditions. Previous works on how to operate electromagnetic systems to reduce defects are discussed based on results from plant experiments, validated computational models, and lab scale model experiments.

The effect of adding elements to promote phase separation on the functional properties of medium-entropy alloys has rarely been reported. In this paper, medium-entropy alloys with dual FCC phases were prepared by adding Cu and Ag elements, which exhibited a positive mixing enthalpy with Fe. Dual-phase Fe-based medium-entropy alloys were fabricated via water-cooled copper crucible magnetic levitation melting and copper mold suction casting. The effects of Cu and Ag elements microalloying on the microstructure and corrosion resistance of a medium-entropy alloy were studied, and an optimal composition was defined. The results show that Cu and Ag elements were enriched between the dendrites and precipitated an FCC2 phase on the FCC1 matrix. During electrochemical corrosion under PBS solutions, Cu and Ag elements formed an oxide layer on the alloy’s surface, which prevented the matrix atoms from diffusing. With an increase in Cu and Ag content, the corrosion potential and the arc radius of capacitive resistance increased, while the corrosion current density decreased, indicating that corrosion resistance improved. The corrosion current density of (Fe63.3Mn14Si9.1Cr9.8C3.8)94Cu3Ag3 in PBS solution was as high as 1.357 × 10−8 A·cm−2.

For studying the changes of macro-physical field in the casting process of large-scale rare earth magnesium alloy, through the numerical simulation method, a two-dimensional axisymmetric multi-physical field coupling model was established by using the multi-physical simulation software COMSOL Multiphysics. The changes of temperature field, flow field, Lorentz force, and liquid fraction of large-size rare earth magnesium alloy with diameter of 750 mm under different electromagnetic parameters (magnetic field frequency and current intensity) in steady state of direct-chill (DC) casting were studied. The results reveal that using a magnetic field can reduce the temperature gradient and greatly accelerate the melt flow, the depth of the sump is reduced by about 50 mm. As the current intensity rises, the flow rate in the melt becomes accelerated, the sump depth becomes shallower, while the melt area with a liquid fraction of 0.5 to 0.63 increases. The Lorentz force rises as the magnetic field frequency increases, but the skin depth of the magnetic field decreases from 64.9 to 36.4 mm.

The thin slab casting (TSC) is a breakthrough near-net-shape technique for flat products accompanied by rapid casting and solidification rates. The TSC quality hinges on the turbulence, super-heat flow and growth of the solidified shell. The electromagnetic brake (EMBr) is commonly applied to control the fresh melt flow after feeding through a submerged entry nozzle (SEN). Numerical modelling is a perfect tool to investigate the multiphase phenomena in the continuous casting (CC). The presented study considers the heat transfer through the solid shell and water-cooled copper mold including the averaged thermal resistance of the slag skin and the air gap coupled with the turbulent flow and magnetohydrodynamics (MHD) model using an in-house code developed inside the open-source computational fluid dynamics (CFD) package OpenFOAM®. The model is applied to investigate different undesired asymmetric melt flow issues: (i) with the misaligned or (ii) partially blocked SEN; (iii) caused by the mean flow fluctuations with the natural frequencies; (iv) related to the oscillations of the fresh melt jets for the specific SEN designs and casting regimes. The variation of the flow pattern and superheat distribution is studied and presented for different scenarios both with and without applied EMBr.

Macrosegregation is one of the most frequently observed defects in continuous casting blooms, which causes nonconformity in ultrasonic flaw detection of rolled products. To investigate the influence of combined EMS modes (M-EMS + F-EMS) on macrosegregation, a 3D multiphase solidification model based on the volume-averaged Eulerian approach was established to simulate the electromagnetic field, fluid flow, microstructural evolution, and solute transport of heavy-rail steel blooms subjected to different EMS processes. In this model, a hybrid model of the mushy zone and a back-diffusion model were introduced into the momentum and solute conservation equations to realize the calculation of microstructural evolution and solute transport with electromagnetic stirring. The predicted magnetic induction intensity, macrostructure, and macrosegregation were verified with Tesla meter measurements, etched macrostructure analysis, and infrared carbon-sulfur analysis. The calculation results showed that M-EMS had little effect on the improvement of the positive centerline segregation, whereas F-EMS effectively reduced the positive centerline segregation. Moreover, a combination of these EMS modes could further reduce the positive centerline segregation in continuous casting blooms. The change in solute concentration caused by M-EMS could be inherited by the position of F-EMS, which could enhance the metallurgical effects of F-EMS. These results were also verified through an industrial application.

Understanding and reducing defects formed during continuous casting of steel are challenging because of the many inter-related, multiscale phenomena and process parameters involved in this complex process. Solidification occurs in the presence of turbulent multiphase flow, transport and capture of particles, superheat transport, and thermal–mechanical behavior. The application of electromagnetic fields provides an additional parameter to control these phenomena to reduce solidification defects. It is especially attractive because the field has the potential to be easily adjusted during casting to accommodate different casting conditions. This article briefly reviews how electromagnetic forces affect solidification defects, including subsurface hooks, particle capture, deep oscillation marks, depressions, cracks, breakouts, segregation, and shrinkage. This includes the related effects on superheat transport, initial solidification, surface quality, grain structure, internal quality, and steel composition distribution. Finally, some practical strategies regarding how to apply electromagnetics to improve steel quality are evaluated.

During continuous casting, electromagnetic braking (EMBr) is a widely used technology to improve the quality of steel product. The EMBr technology takes benefit of the generation of Lorentz forces that are induced by the interactions of melt flow with externally applied magnetic fields. In the present paper we propose and investigate a new type of EMBr, named vertical-combined electromagnetic braking (VC-EMBr) in application to the Compact Strip Production (CSP) thin slab continuous casting mold. The unique characteristic of the VC-EMBr lies in the fact that two new pairs of vertical magnetic poles (VMPs) are located adjacent to the mold narrow faces on the basis of Ruler-EMBr. To determine the braking effect of the VC-EMBr, the influence of the installation position of the VMPs on the flow, heat transfer and solidification behaviors of ultra-low carbon steel in a 1500 × 70 mm CSP funnel-type mold is numerically solved. The fluid-flow-related phenomena of three casting cases in the CSP mold, i.e., No-EMBr, Ruler-EMBr, and VC-EMBr, are further investigated numerically to evaluate the metallurgical capability of the VC-EMBr, including the quantitative evaluation of level fluctuation, heat transfer, and shell growth at a casting speed of 4.5 m/min. The parametric study shows that for the CSP mold with width of 1500 mm, the optimal braking effect of the VC-EMBr can be obtained when the VMPs are located at 50 mm from the narrow face of the mold. With this adjustment, the magnitude of the maximum surface velocity is reduced by 70 pct when compared to the case of p1 = 0 mm. This reduction can decrease the heat loss in the upper recirculation region of the CSP mold and promote the homogeneity of the temperature field therein. In addition, the evaluation results show that the newly proposed VC-EMBr provides more obvious technological advantages than the traditional Ruler-EMBr in application to the CSP mold with a bifurcated nozzle. For the VC-EMBr, the horizontal magnetic poles (HMPs) keep the same advantage as the Ruler-EMBr in providing a good protection against excessive downward impact of the molten steel. On the other hand, the VMPs overcome the disadvantage that the Ruler-EMBr cannot well suppress the upward backflow in the CSP mold. For instance, by applying a magnetic flux density of 0.3 T, the VC-EMBr has a better capability to reduce the maximum amplitude of the level fluctuation by 83.8 pct and increase the average surface temperature of the molten steel from 1803.6 K to 1804.5 K when compared to the case of Ruler-EMBr. This variation can well prevent surface defects related to the level fluctuation, such as slag entrapment and mold powder freezing. On this basis, it can be seen that the industrial application of the VC-EMBr in the CSP mold can benefit from these findings.