Electromagnetic Casting Research Articles

Development of the manufacturing technique of crucibles to melt aluminum and improve its physical and mechanical properties by microwave oven

There are several techniques that are used to melt metal materials, among which we have conventional casting, by agitation, by compression and by molding. It is currently being studied in a technique based on electromagnetic radiation with the implementation of conventional microwave oven, thus improving the results in terms of time in the casting process; to carry out this electromagnetic casting process, a high-frequency wave-receiving medium is required to reach the melting temperature of the material on which it is being worked. In the case of aluminum, a working temperature of approximately 700 °C is required to achieve phase change of the material. This project produces a fine-grained silicon carbide-based crucible, taking into account that it is a semiconductor and refractory material capable of capturing electromagnetic waves, for the purpose of allowing the use of a microwave oven in the aluminum smelting process; presenting in this way a new casting technique that promises a significant saving in the execution time and saving the implementation process in recycling and reuse of aluminum and improving its physical and mechanical properties by means of irradiation casting electromagnetic.

Effect of Low-Frequency Electromagnetic Casting on Micro-Structure and Macro-Segregation of 5A90 Alloy Ingots.

The effect of low-frequency electromagnetic fields on the micro-structure and macro-segregation of 5A90 alloy ingots during the semi-continuous casting process were quantitatively investigated. The ingots of a 5A90 alloy with a diameter 170 mm were produced by the conventional direct chill casting (DCC) process and low-frequency electromagnetic casting (LFEC) with 10 Hz/100 A. The results showed that LFEC can substantially refine the micro-structure and shorten the width of the columnar grain area of an ingot. The refinement effect came with the relieving of grain boundary segregation and an improvement in the macro-segregation of the ingot. Compared with the traditional DCC process, the tensile properties of the aged alloy prepared by the LFEC process were improved due to the effects of the increase in solid solubility and the strengthening of the grain refinement, so that the stability of the tensile properties was also improved. Meanwhile, the rate of yield increased by 2.3% with a decrease in the peeling thickness of the ingot.

Structure and Properties of Al–0.6wt.%Zr Wire Alloy Manufactured by Direct Drawing of Electromagnetically Cast Wire Rod

The method of electromagnetic casting (EMC) was used to produce the long-length rod billet (with a diameter 12 mm) of aluminum alloy containing 0.6 wt.% Zr, 0.4%Fe, and 0.4%Si. The combination of high cooling rate (≈104 K/s) during alloy solidification and high temperature before casting (≈830 °C) caused zirconium to dissolve almost completely in the aluminum solid solution (Al). Additions of iron and silicon were completed in the uniformly distributed eutectic Al8Fe2Si phase particles with an average size of less than 1 µm. Such fine microstructure of the experimental alloy in as-cast state provides excellent deformability during wire production using direct cold drawing of EMC rod (94% reduction). TEM study of structure evolution in the as-drawn 3 mm wire revealed the onset of Al3Zr (L12) nanoparticle formation at 300 °C and almost-complete decomposition of (Al) at 400 °C. The distribution of Zr-containing nanoparticles is quite homogeneous, with their average size not exceeding 10 nm. Experimental wire alloy had the ultimate tensile strength (UTS) and electrical conductivity (EC) (234 MPa and 55.6 IACS, respectively) meeting the AT2 type specification. At the same time, the maximum heating temperature was much higher (400 versus 230 °C) and meets the AT4 type specification.

Low Frequency Electromagnetic Casting of 2195 Aluminum–Lithium Alloy and Its Effects on Microstructure and Mechanical Properties

In this study, the low frequency electromagnetic casting (LFEC) technology was adopted to fabricate 2195 Al–Li alloy. The microstructure and solid solubility of as-cast 2195 alloys, as well as the second phase precipitation and tensile properties after aging, were investiagated and compared with the counterpart direct chill casting 2195 alloy. Our results indicate that LFEC can significantly improve the microstructure and metallurgical quality of as-cast alloy, and increase the number density of θ′ (Al2Cu) and T1 (Al2CuLi) phases during aging treatment due to the enhanced solubilities of alloying elements. The tensile properties of 2195 aged alloy cast by LFEC were hence improved evidently.

Numerical and analytical approach for Sakiadis rheology of generalized polymeric material with magnetic field and heat source/sink

In this analysis, Sakiadis rheology of the generalized polymeric material has been presented with magnetic field and heat source/sink. Convective heating process with thermal radiations have been incorporated. Mathematical modeling has been performed for the conversion of physical problem into set of non-linear equations. Suitable transformations have been employed in order to convert the derived PDE into set of non-linear ODE. Analytical as well as finite difference method based numerical solutions for the velocity and temperature profiles are computed. Graphical and numerical illustrations have been presented in order to analyze the behavior of involved physical quantities. Error analysis for the non-linear system has been presented in order to show the validity of the obtained results. Bar charts have been plotted to present the heat flux analysis. Tabular values of local Nusselt number are computed for the involved key parameters. Heat transfer rates against magnetic and porosity effects found to be decreased since magnetic field and porosity retard the molecular movement of the fluid particles. This controlling property of magnetic field and porosity effects have application in MHD power generation, electromagnetic casting of metals, MHD ion propulsion, etc. Moreover internal heat generation and absorption effects have opposite effects on the fluid temperature.

Study on micro-structure, solid solubility and tensile properties of 5A90 Al–Li alloy cast by low-frequency electromagnetic casting processing

In this paper, the low-frequency electromagnetic casting (LFEC) processing was introduced as an efficient pollution-free casting technique, and how it influenced the micro-structure and mechanical properties of 5A90 Al–Li alloy was investigated. The mechanical properties of the alloy had a close connection with the casting metallurgical quality and the precipitation phases. Compared to the conventional direct chill casting (DCC), the LFEC could promote the precipitate of the δ′ (Al3Li)/β′ (Al3Zr) and reduce the width of PFZ, which enhanced the effect of the precipitation strengthen and alleviated the strain localization. Meanwhile, the micro-structure of the ingot was refined significantly and the metallurgical quality was improved after LFEC treatment due to the modification of the flow and temperature field of the sump that caused by the application of low-frequency electromagnetic field. Maximum yield strength and ultimate tensile strength of as-aged alloy cast by LFEC with 150 A/15 Hz could reach 371.85 MPa and 495.5 MPa, while elongation remained at 9.82%.

Effect of electromagnetic casting process on microstructure and properties of AZ31 magnesium alloy

ABSTRACTIn this paper, AZ31 magnesium alloy is cast by applying the semi-continuous casting process with a low-frequency electromagnetic field. By studying the influence of electromagnetic field frequency, excitation current intensity and casting velocity on the microstructure and mechanical properties, the optimum process under oil-slip electromagnetic casting conditions was determined to improve the degree of grain refinement, yield strength, elongation and tensile strength of AZ31 alloy. An improved microstructure refining effect and higher hardness can be obtained with a current intensity af 60 A. The microstructures and mechanical properties obtained for different casting velocities of V = 200 mm/min and V = 230 mm/min at processing parameters of f = 30 Hz and I = 120 A were compared. Our results suggest that a higher casting speed does not lead to grain refinement or improved mechanical properties. Frequency

Structure and Properties of Al-0.6%Zr-0.4%Fe-0.4%Si (wt.%) Wire Alloy Manufactured by Electromagnetic Casting

The experimental Al-0.6%Zr-0.4%Fe-0.4%Si alloy has been manufactured by using the method of electromagnetic casting. It is shown that Zr is completely dissolved in the aluminum solid solution (Al) and iron is fully included in the Al8Fe2Si phase. The fine microstructure of the as-cast rod implies a high deformation plasticity, which has been experimentally confirmed during wire production. The cold-rolled wire has an ultimate tensile strength (UTS) ~ 260 MPa, and subsequent annealing at 400°C for 3 h slightly reduces the strength, which is associated with the stabilizing effect of the L12 (Al3Zr) phase nanoparticles formed during annealing. Annealing also leads to a significant increase in the specific conductivity, the value of which reaches 57.0 IACS. Drawing of the annealed rolled wire leads to significant strengthening. Annealing at 400°C leads to a marked strength reduction, which, however, remains high enough for conductive alloys (UTS higher than 200 MPa).

Effect of extrusion on the microstructure and thermomechanical behavior of continuously electromagnetic casting AZ31

The thermal deformation behaviour of semi-continuously electromagnetic casting AZ31 magnesium alloy was investigated by compression tests with strain rate controlled for 0.001 ∼ 0.1 s−1 at 473 K ∼ 623 K. A detailed analysis with respect to the influencing parameters was then conducted based on the true stress-strain curve, including calculating the deformation activation energy under various magnetic field conditions.Extrusion tests of AZ31 alloy under different casting conditions were performed. The testing parameters were optimized by the available hot compression data. The fracture morphology of pre- and post-deformation were compared to evaluate the effects of casting conditions on the microstructures and performances of the extrusion bars.The results show that dynamic recrystallization takes place under all the experimental conditions. The stress-strain curve exhibits a peak firstly, and then a drop followed to a stable stage with the subsequent strain accumulation. The value of the stable stage decreases with the increase of temperature but decrease of the strain rate. The dynamic recrystallization leads to a refinement of the grains and hence enhanced the mechanical performance of the materials. In addition, a hereditary effect was found on the properties of the extrusion AZ31 alloys for electromagnetic field frequency.

Micro-Structure and Mechanical Properties of 2A97 Al-Li Alloy Cast by Low-Frequency Electromagnetic Casting

In this paper, the micro-structure and solid solubility of 2A97 aluminum-lithium alloy ingots prepared by conventional direct chill (DC) casting and low frequency electromagnetic casting (LFEC) as well as the density of precipitates and tensile properties of 2A97 alloy after T6 treatment were investigated. The results show that the low-frequency electromagnetic field during casting had a remarkable effect on the refinement of micro-structure and solid solubility of alloying elements within the grains, which is very helpful to obtain a large number of fine, uniformly-distributed T1 phases. The mechanical properties of 2A97 alloy prepared by low frequency electromagnetic casting after T6 treatment were improved by obtaining a larger number T1 phases.

Excellent mechanical properties obtained by low temperature extrusion based on Mg-2Zn-1Al alloy

A newly developed low Al containing magnesium alloy, Mg-2Zn-1Al based alloy (wt.%) shows excellent mechanical properties. The alloys with superior high strength and considerable ductility (the maximum of tensile strength reaches 332 MPa and corresponding elongation is 23.1%) were produced by electromagnetic casting and extrusion at relatively low temperatures (110 °C, 170 °C, 210 °C, and 250 °C) with an extrusion ratio of 17.4:1. Effects of extrusion temperature on the evolution of microstructure, mechanical properties and extruded texture were investigated by OM, SEM, TEM, and EBSD analysis. The microstructures of the alloy extruded at low temperatures mainly consist of the equiaxed dynamically recrystallized grains, elongated grains, and regions without dynamic recrystallization. And there are only equiaxed dynamically recrystallized grains in the alloy extruded at 250 °C. The increasing extrusion temperature results in grain coarsening and strength reduction. When the extrusion temperatures are 110 °C and 170 °C, the average grain size reaches submicron level of 0.65 μm and 0.89μm, respectively. Because the higher extrusion temperature makes the dynamically recrystallized grains rotate in a favorable direction, the basal texture enhances with the rise of extrusion temperature. The high strength is mainly attributed to the structure of extremely refined grains. High ductility benefits from a large amount of basal slip, activation of non-basal slip, and grain boundary movement under the action of tensile stress.

Impact of Magnetic Field and Second-Order Slip Flow of Casson Liquid with Heat Transfer Subject to Suction/Injection and Convective Boundary Condition

The present article is planned theoretically to throw light on non-Newtonian Casson liquid flow and heat transport analysis over an exponentially stretching sheet with second-order velocity slip condition. The analysis of magneto-hydrodynamic (MHD) is an important interdisciplinary field. One of the most imperative applications related to engineering problems is plasma confinement, liquid-metal cooling of nuclear reactors, and electromagnetic casting. The flow here is considered to be electrically conducting. The modelled equations of mass, momentum and energy transport are reduced into the nonlinear ordinary differential equations by employing a similarity approach which are then solved numerically by employing finite difference collocation process (a three-stage Lobatto IIIa scheme). The inspiration of convergence flow parameters on dimensionless velocity, temperature have been discussed graphically. The obtained results confirm that an excellent agreement is achieved for the Newtonian case with those available in the literature. Consequences establish that skin friction rises in the presence of Casson fluid parameter and the Nusselt number show enhancement for second order slip parameter.

Effects of electromagnetic field on physical behaviors during low-frequency electromagnetic casting of Mg alloy AZ31

A numerical model was established for the simulation of the multiple physics fields during the low-frequency electromagnetic casting (LFEC) process of AZ31 alloy by using ANSYS (FE commercial package) and FLUENT (finite volume package). The electromagnetic field was calculated in the former and the latter was aimed at analyzing the fluid flow driven by magnetic, heat transfer and solidification. Overall physical parameters, including magnetic flux density, Lorentz force, flowing velocity, temperature field and liquid cave feature were discussed. Results show that the electromagnetic field can significantly affect the flow field and temperature field of the melt during the LFEC process of AZ31 alloy by inducing the effect of Lorentz force. Different electromagnetic frequencies have different effects. In the experimental frequency range of 5 ∼ 35 Hz, a higher frequency can intensify the flowing of the melt near the cooled wall of the crystallizer, resulting in an increase in heat transfer intensity and further a decrease in liquid cavity depth.

Numerical study on action of HMF, PMF, DHMF, and DPMF on molten metal during electromagnetic casting

The effect of harmonic magnetic field (HMF), pulse magnetic field (PMF), differential phase harmonic magnetic field (DHMF), and differential phase pulse magnetic field (DPMF) on liquid and mushy zones of crystallizing metal was investigated by numerical simulation referring to electromagnetic DC (direct chill) casting process. Firstly, the experimental pulse current for electromagnetic casting was obtained by a digital oscilloscope. The physical and finite element models of Φ300-mm cylindrical crystallization for the electromagnetic field simulation were established. Then, the distribution of magnetic flux density (B) and electromagnetic forces (FMAG) generated by the four types of magnetic fields were obtained in a period (T). Actions of HMF, PMF, DHMF, and DPMF on molten melt were discussed based on radial and axial electromagnetic forces. Finally, the effects of electromagnetic parameters (current intensity, frequency, and duty cycle) on electromagnetic forces under PMF and DPMF were studied. The effect of electromagnetic forces on metal flow has been discussed. The results indicate that compared with harmonic current, the pulse current can generate a stronger magnetic field with the same conditions. Single-coil magnetic field can easily cause the molten metal radial vibration. The differential phase magnetic field can not only cause radial vibration but also produce axial convection, while the vibration effect is weaker. The electromagnetic forces increase with the increase of current intensity and duty cycle under PMF and DPMF. Moreover, the electromagnetic force has low sensitivity to frequency under DPMF.

Solution to a three-dimensional axisymmetric inverse electromagnetic casting problem

ABSTRACTA new method based on topology optimization is proposed for solving a three-dimensional axisymmetric inverse problem regarding the configuration of electric currents used in the electromagnetic casting technique of the metallurgical industry. These electric currents must generate an electromagnetic field such that when certain mass of liquid metal is placed in the field it levitates acquiring a predefined axisymmetric shape. The method proposed is able to obtain a suitable configuration of electric currents, and is very attractive from the computational point of view, since it is based on a sparse convex quadratic programming formulation for which there are very efficient interior-point solution algorithms.

Critical review on liquid state processing of aluminium based metal matrix nano-composites

Abstract Liquid state processing of aluminium based metal matrix nano-composites (MMNCs) along with their microstructures are reviewed critically from open literature. Results obtained by many researchers reveal that mechanical milling followed by stir casting can produce the nano-composites with reduced grain size, strong interfacial bonding and homogeneous dispersion with little agglomeration of reinforcements. Ultrasonic assisted casting reduces the agglomerations and improves wettability of the nano-particles. MMNCs with well dispersed reinforcements on the grain boundaries can be produced through induction melting process. Electromagnetic casting reduces the cracks and cavity defects; whereas spray forming and disintegrated melt deposition technique produce near-net structured MMNCs with homogeneous distribution of nano-particles. Finally, some grey area on liquid state processing of aluminium MMNCs has been identified and the scope for future research is suggested.

Solution of the equilibrium problem in electromagnetic casting considering a solid inclusion in the melt

A new method is proposed for solving the equilibrium problem related to the electromagnetic casting technique. The method is appropriate for the case when part of the metal is in solid state. It is shown that in the presence of solid inclusions the equilibrium equation of the free liquid boundary can be formulated as a complementarity equation. A Newton-like iteration is then proposed to solve the resulting set of nonlinear equations. Results for some numerical examples are presented, showing that in the case of simple configurations the numerical technique proposed finds solutions in good agreement with the analytical solutions presented in the literature. Examples of more complex situations with solid inclusions represented by level set functions are also solved, showing that the proposed algorithm can be reliably used to find equilibrium configurations.

Numerical analysis of three-dimensional MHD natural convection flow in a short horizontal cylindrical annulus

A numerical study of three-dimensional (3D) MHD laminar flow in a short horizontal cylindrical annulus has been performed to characterize the impacts of a uniform axial magnetic field on both hydrodynamic and thermal behaviors. This configuration corresponds to a horizontal annular mold containing molten iron or low carbon steel in electromagnetic casting (EMC). Complex nonlinear governing equations are solved numerically by means of the finite volume method based on artificial compressibility algorithm. The induced electric potential caused by the magnetic field is considered. Results show that a typical 3D steady spiral flow arises and the symmetry breaking occurs under a weak magnetic field of Ha < 10. As the Hartmann number increases, the spiral flow is distinctly suppressed, and then it changes to a helical flow with two transverse cells adjacent to each of the end walls. Correspondingly, the flow patterns and isotherms of fluid become symmetric with respect to the mid-axial plane of the annulus. Further increasing the Hartmann number, the fluid particle trajectories essentially lie in the cross-section of the annulus, as for two-dimensional solutions, with an extremely small axial dependency. In addition, both the values of local Nusselt number at the isothermal walls and its axial dependency, mainly in the upper region (−38π≤φ≤38π), are significantly affected by the magnetic field. The results of the present work can be useful in producing high-quality products by magnetic control.

Joule heating in magnetic resistive flow with fractional Cattaneo–Maxwell model

Influence of electric and magnetic fields in a nonlinear viscoelastic flow is studied in this communication. Microscopic description of Joule heating can be seen with the proposed model. Fractional formulation of the problem with Cattaneo–Maxwell model leads to oscillation and relaxation processes that show memory and delay of thermal and diffusing flux. Abrupt change in temperature and concentration in MHD flow can be controlled with this formalism. Time-dependent flow is governed by highly nonlinear fractional differential equations. Finite-element–finite-difference algorithm is used to solve the fractional coupled fields and flow dynamics problem. Remarkable physical parameters are calculated to signify the importance of problem under observation. Modeled problem can be tackled in numerous ways to obtain accurate simulations in polymer and electromagnetic casting industries.

The Influence of Homogenization on the Elemental Distribution and Properties of Cu-10Ni-1Fe-1Mn Alloy Ingot

A set of Cu-10Ni-1Fe-1Mn alloys were prepared. Electromagnetic casting, DC casting ingot organization, properties and composition distribution of the alloy were studied using Optical Microscope (OM), Scanning Electron Microscopy (SEM), Energy spectrum analysis (EDS), Xray diffraction (XRD), Brinell Hardness Test, and electrochemical tests. The results suggested that homogenization of the Cu-10Ni-1Fe-1Mn alloy changed its properties and distribution of composition. The results also suggest that electromagnetic casting can refine casting organization, homogenize the composition of the alloy, and the casting mechanical performance is superior compared to those of DC casting. However, the composition between Dendritic branch and Dendrites was still not homogeneous. After 1 h of homogenization treatment at 950°C, the ingot composition distribution became more homogeneous, and its stiffness decreased. The tube prepared by squeezing the homogenized ingot, was soaked in 3.5% NaCl solution for 240 h, after which the tube blank surface remained a bright metal luster and XRD analysis indicated that a Cu2O protective film of high density covered the surface of the tube. The homogenization treatment significantly improved the corrosion resistant properties of the alloy tubes.