Electromagnetic Stirring Process Research Articles

Numerical and Experimental Study on Carbon Segregation in Shaped Billet of Medium Carbon Steel with Combined Electromagnetic Stirring

Carbon segregation is the major and classical internal defect in the continuous casting process of carbon steel. Based on the combined electromagnetic stirring equipment for new billet in a steel plant, China, the influence of combined electromagnetic stirring (M-EMS + F-EMS) on the carbon segregation of 300 mm × 340 mm special-shaped billet was studied via numerical simulation and on-site industrialization tests. The Lorentz force and carbon solute distribution were simulated under different EMS parameters. The formation mechanism of the carbon segregation of medium carbon steel with different combined electromagnetic stirring processes was analyzed. The results show that: (1) with the combined action of “solute flushing” effect and gravity, the carbon concentration in the loose side of the medium carbon steel casting billet is gradually lower than the fixed side, while the carbon concentration on the fixed side gradually accumulates more; and (2) under the action of combined electromagnetic stirring, the segregation index of casting billet could be controlled to remain between 0.96–1.05 and shows an increasing change in solidification from the skin to the center. When the current and frequency of M-EMS are 250 A and 2.0 Hz and the F-EMS are 180 A and 8.0 Hz, the carbon segregation defects in the special-shaped (300 mm × 340 mm) casting billet can be significantly improved.

Effect of Stroke Length (50 mm and 100 mm) on the Dry Reciprocating Wear Characteristics of Refined and Unrefined A390 Alloy

The present work reports the influence of stroke lengths viz. 50 mm and 100 mm on the reciprocating wear characteristics of refined and unrefined hyper eutectic aluminium silicon alloy (A390). The refined A390 alloy was prepared through the electromagnetic stirring process along with the addition of 0.1 wt.% Al–5Ti–B grain refiner. The wear tests were performed in an indigenously developed pin on reciprocating plate tribometer conforming to ASTM G 133-05 standard. The microstructure had shown the refinement of eutectic silicon and decrease in size of polyhedral primary silicon particles due to the combined action of grain refiner addition and electromagnetic stirring. Refined and unrefined A390 alloys were heat treated under T6 condition. Hardness of the refined A390 alloy (107 BHN) was higher than that of unrefined A390 alloy (89 BHN). Reciprocating wear tests were conducted at two stroke lengths with contact loads varied from 15 N to 60 N and the linear velocity from 0.2 m/s to 1.0 m/s for a constant sliding distance of 350 m. During the wear tests it was observed that as the velocity varied from 0.2 m/s to 0.4 m/s the wear loss was found to decrease at both stroke lengths tested for refined and unrefined samples, further increase in velocity increases the wear rate. As the stroke length varied from 50 mm to 100 mm the wear loss was found to decrease for both refined and unrefined alloys. This reduction in wear loss with increase in stroke length was due to the reduced reversals of load happening at larger stroke length (100 mm) also the frequency of reciprocation is high at 50 mm stroke length compared to that at 100 mm for the similar sliding conditions tested.

Effects of Electromagnetic Stirring process on Melt Quality of A356 Aluminum Alloy

Effects of Electromagnetic Stirring process on Melt Quality of A356 Aluminum Alloy

Multi-physics coupling simulation investigation of semi-solid A380 aluminum alloy during intermediate frequency electromagnetic stirring process

Multi-physics coupling simulation investigation of semi-solid A380 aluminum alloy during intermediate frequency electromagnetic stirring process

Research microstructure and mechanical properties of AZ31 magnesium alloy by semisolid extruding with electromagnetic stirring process

Research microstructure and mechanical properties of AZ31 magnesium alloy by semisolid extruding with electromagnetic stirring process

Numerical Analysis of an Electromagnetic Stirring System for Composite Plastic Materials with Ferromagnetic Particles

AbstractThis paper deals with a Finite Element (FE) numerical analysis of an electromagnetic stirring system for composite plastic materials with ferromagnetic particles. The electromagnetic stirring process is ensured by the magnetic forces acting on the ferromagnetic particles spread in the plastic matrix. These forces are produced by the rotating magnetic field of the stator of a three‐phase induction motor supplied from an inverter. The analysis is carried out using the professional software package Flux for electromagnetic field computation based on the FE method. The 2D computations allowed to estimate the magnetic forces and their orientation acting on micrometric particles spread in a fluid plastic material. A preliminary experimental setup is also built for studying the proposed solution.

Effect of EMS Process on the Primary Si Refinement, Tensile and Fatigue Properties of Hyper-eutectic Al-15wt.%Si Alloy

This study investigated the effect of the electromagnetic stirring (EMS) process on the microstructure and mechanical properties of hyper-eutectic Al-15 wt.%Si alloy. The tensile and high-cycle fatigue properties of the EMS Al-15wt.%Si alloy were examined and compared with conventional direct chill (DC) cast alloy. The initial microstructure of the as-cast DC alloy showed a coarse primary Si of 70 µm, in contrast to the size (40 µm) of the as-cast EMS alloy. The DC extruded alloy exhibited a massive primary Si size of 40~55 µm. In contrast, the EMS extruded alloy had a spherical primary Si with 30~40 µm sizes. The average grain sizes were measured to be 8.8 µm (EMS extruded alloy) and 11.4 µm (DC extruded alloy), respectively. The EMS process was confirmed to contribute to the refinement of the grain size and the primary Si size of the hyper-eutectic Al-Si alloy. The yield strengths at room temperature were measured to be 388.0 MPa (EMS extruded alloy) and 375.0 MPa (DC extruded alloy), and the tensile strengths were 426.0 MPa (EMS extruded alloy) and 412.4MPa (DC extruded alloy), respectively. The elongations of both alloys were similar at room temperature. The fatigue limit of the EMS extruded alloy (130 MPa) was higher than that of the DC extruded alloy (120 MPa). The EMS extruded alloy exhibited superior fatigue resistance compared to the DC extruded alloy, regardless of the cyclic stress condition. This study also discussed the potential value of the EMS process as a method for improving the properties of hyper-eutectic Al-Si alloy, as well as the deformation and fracture mechanisms of the EMS Al-15wt.%Si alloy.

Effect of titania‐silver nanocomposite particle concentration and thermal cycling on characteristics of sodium dodecyl sulfate added paraffin wax thermal energy storage material

AbstractThe present work focuses on analyzing the thermal properties of 0.5, 1 and 1.5 wt% of titania‐silver nanocomposite particles dispersed paraffin wax (NCDPW) PCM without and with sodium dodecyl sulfate (SDS) surfactant for both non‐cycled and thermal cycled samples. NCDPW without and with SDS was prepared using electromagnetic stirring and ultrasonication process. 1 wt% titania‐silver NCDPW with SDS in the mass ratio of 1:0.25 (NCP:SDS) is identified as optimum with an enhancement in thermal conductivity of 66.59%, better thermal decomposition stability upto 372°C, good physical interaction between nanocomposite particles (NCP) and paraffin wax (PW). Also, an enhancement in thermal storage efficiency (97.15%), reduction in onset melting time (35.50%) and onset freezing time (29.23%) compared to PW even after several thermal cycling process is achieved. Further, it showed a reduction in melting onset temperature to 59.2°C, an enhancement in melting heat capacity potential by 7.2% and freezing heat capacity potential by 7.7% after thermal cycling process. On the whole, the thermal properties of the base PW are increased due to the addition of titania‐silver NCP with SDS proving it, a promising energy storage medium for thermal energy storage.

Formation of non-dendritic microstructures in preparation of semi-solid Mg-RE alloys slurries: Roles of RE content and cooling rate

Abstract The proper alloy composition ranges for rheo-forming of Mg-RE alloy was obtained through thermodynamic calculations. The low frequency electromagnetic stirring (LFEMS) process was used to fabricate semisolid slurries of Mg-Gd-Zn series alloys, and the role of solute Gd content and the cooling rate in the LFEMS process were systematically investigated. Both the Gd content and cooling rate show effective influences on the microstructure of the Mg-Gd-Zn alloy semisolid slurries. Fine and spherical primary Mg phase can only be obtained by decreasing the cooling rate to less than 1.4 C°/min and increasing the solute Gd content to no less than 9 wt.%. The formation mechanism of non-dendritic morphology of primary Mg phase in Mg-Gd-Zn alloy was proposed to be the dendrite arm root re-melting induced by curvature undercooling and ripening induced by low cooling rate.

Experimental investigation of the effect of travelling magnetic field on the CET in Sn-10wt.%Pb alloy

In order to eliminate internal and surface defects, which appear in the ingots during solidification process of metallic alloys, homogeneous and fine structures are often required. Therefore, when the adjunction of inoculant substances is not possible, the electromagnetic stirring (EMS) process thanks to the use of travelling magnetic fields has technically shown its effectiveness. The present experiments consist to create convective movements in a Sn-10wt.%Pb liquid metal, by the action of an electromagnetic field during its solidification. A significant improvement in the columnar-equiaxed transition (CET) mechanism has been observed and consequently a fine equiaxed grain structure can then be detected. The main goal of this experimental study is to examine the effect of the EMS process on grain structures for that alloy as well as the corresponding segregations. In particular, it included the determination of the optimal experimental parameters to obtain a grain refinement, the characterization of their effect on the solidification and the understanding of the physical mechanisms driving grain refinement.

Influence of Joint EMSFN and M-EMS on Fluid Flow in the Mold During Continuous Casting

Homogenization of physical properties and the chemical composition through the control of liquid metal flow is essential during the continuous casting production of billets. This work was aimed at obtaining improved finished products via continuous casting that implements two magnetic fields. These fields were realized via two electromagnetic stirring processes implemented in a single process: one in the nozzle and one in the mold. The qualitative effects of applying double electromagnetic stirring (EMS) were verified through numerical simulation of 178 mm × 178 mm square billets exposed to double electromagnetic fields during the continuous casting process. The accuracy of the numerical calculations was verified via physical experiments. In addition, the final simulation results were compared with the intermediate results, to determine the true effects of different EMS on the metal flow in the mold. The results revealed that casting using EMS with different directions of magnetic field in the mold and the nozzle has the best effect on the distribution of the fluid flow and minimal influence on the stability of the meniscus and yields the minimum metal-jet penetration into the mold.

Effects of A-EMS on Microstructure and Mechanical Properties of DC Casting Al-10Si-1.1Ni Alloy

Al-Si alloys were characterized by excellent corrosion and wear resistance, low thermal expansion and high specific strength. Adding Ni to Al-Si alloy contributes to enhance the elevated temperature strength. However, the coarse structures and Ni-containing phases are disadvantageous for the mechanical properties. In this paper, an advanced melt treatment technology named the annular electromagnetic stirring (A-EMS) process was utilized for the Al-10Si-1.1Ni alloy to examine the effects of A-EMS on structures and mechanical properties. Research results showed that in the case of A-EMS, the billets with finer solidification structures and Ni-containing phases morphology as well as higher performance were achieved.

Numerical investigation of in-mold electromagnetic stirring process for fluid flow and solidification

PurposeThe 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/approachA 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.FindingsResults 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 implicationsThe 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/valueThe 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.

Reducing macro segregation of high carbon steel in continuous casting bloom by final electromagnetic stirring and mechanical soft reduction integrated process

The influence of final electromagnetic stirring (F-EMS) combined with mechanical soft reduction (MSR) on reducing macro segregation has been investigated in order to improve inner quality of high carbon steel bloom with 1 wt.% carbon. A 2D heat transfer model was developed to predict the solidification process of bloom by taking into account thermo-physical properties which were obtained by experiments. The predicted surface temperature and shell thickness were verified by infrared temperature and nail shooting measurement results, respectively. In addition, roll-gap calculation model was established by a segmented slope method to calculate the proper soft reduction zone and determine the distribution of total reduction amount. The optimum F-EMS implement position and soft reduction zone with the goal of minimum macro segregation of high carbon steel bloom were theoretically determined by the heat transfer model associating with high temperature tensile test. The industrial research results showed that macro segregation has been significantly improved by the optimum combination with F-EMS and MSR processes, and the risk of center negative segregation and internal cracks could be avoided by modifying F-EMS implemented position and the distribution of total reduction amount. Besides, compared with the combination of mold electromagnetic stirring (M-EMS) and F-EMS processes, the reasonable center solid fraction of bloom at the F-EMS implemented position in F-EMS and MSR integrated process was much lower.

Rheo-Forming AZ91D Magnesium Alloy Using Enthalpy Equilibrium Electromagnetic-Stirring Process

An enthalpy equilibrium electromagnetic-stirring process was introduced to semisolid metal processing for rheoforming route. AZ91D was die-casted under normally liquid state of Mg alloy, semisolid state of Mg alloy stirred using traditional EM-stirrer and an enthalpy equilibrium EM-Stirrer, respectively. Further step, effect of pouring temperature on microstructures and tensile properties of castings was researched in the introduced process. Experimental results indicated that samples of rheo-diecasted in the introduced process showed globular primary solid particle microstructure and better comprehensive mechanical properties, typical microstructures consisting of globular primary α-Mg grains and pseudoeutectic organization was observed in the castings with low solid fraction, while in higher solid fraction, the microstructure comprised of agglomerating primary solid particles and Mg17Al12 of divorced eutectic. With decreasing pouring temperature, the density of primary solid particles increased greatly, the size of primary solid particle evolved to coarse.

A novel method of increasing ceramic shell permeability and optimizing casting shrinkage and tensile strength of the investment cast parts

This study explores about enhancing the permeability of the ceramic shells used in the investment casting process using cheaply available sawdust particles. An increase in shell’s permeability augments the cooling rate of the casting which enhances its mechanical properties. It was found that the inclusion of sawdust particles into the ceramic slurries exhibited positive impact on the shell’s permeability. It is a well-known fact that electromagnetic stirring process increases the mechanical properties of the castings, but its effect on casting shrinkage has never been realized. Thus, this study further throws light on the impact of electromagnetic stirring in reducing the shrinkage and improving the tensile strength of the casting. In a nutshell, it was found that the final product quality of the investment cast part improved by the combinational treatments adopted in this research work.

Study on rheo-diecasting process of 7075R alloys by SA-EMS melt homogenized treatment

An advanced melt processing technology, spiral annular electromagnetic stirring (SA-EMS) based on the annular electromagnetic stirring (A-EMS) process was developed for manufacturing Al-alloy components with high integrity. The SA-EMS process innovatively combines non-contact electromagnetic stirring and a spiral annular chamber with specially designed profiles to in situ make high quality melt slurry, and intensive forced shearing can be achieved under high shear rate and high intensity of turbulence inside the spiral annular chamber. In this paper, the solidification microstructure and hardness of 7075R alloy die-casting connecting rod conditioned by the SA-EMS melt processing technology were investigated. The results indicate that, the SA-EMS melt processing technology exhibited superior grain refinement and remarkable structure homogeneity. In addition, it can evidently enhance the mechanical performance and reduce the crack tendency.

Study on Grain Refinement and Homogenization of Large-Sized DC Casting Ingot by A-EMS Melt Treatment

Electromagnetic stirring (EMS) process, as an advanced melt treatment technology, is increasingly applied in metallurgy industry. Direct chill (DC) casting process by annular electromagnetic stirring (A-EMS) was applied in this study to investigate the solidification behavior of a modified 7N01 alloy, and the effects of DC casting process without EMS, and A-EMS casting process on microstructure, composition segregation and mechanical properties of continuously cast billets were compared. The research results showed that the billets with higher performance, lower macro-segregation, more uniformly fine solidification structure were obtained in case of A-EMS.

Synthesis and Characterization of TiAl‐Based Nanocomposites by a Melt Electromagnetic Stirring Process

Ceramic nanoparticles were considered difficult to be dispersed well in liquid metal, especially in non‐reactive systems, by stir mixing methods due to their high specific surface energy. In this paper, an electromagnetic stirring process was exploited to disperse ceramic nanoparticles in an active TiAl alloy melt. The results indicate that finely dispersed nanoparticles can be obtained by stir mixing with the aid of reactive wetting. The presence of nanoparticles during solidification can refine the primary dendrites dramatically, which was primarily determined by the extent of particle pushing at the liquid–solid interface. Among the studied particles, TiC can refine the (γ + α2) lamellar colonies, which is attributed to the dissolution of carbon and subsequent precipitation of Ti2AlC during L + β → β + α. The Vickers hardness of the nanocomposites as a function of stirring time was tested, and the Ti–45Al/TiC nanocomposite produced by 10 min stir mixing has the highest value, measuring 450 HV.

Multi-objective Optimization of the EMS Processed IC by Grey-fuzzy Method

In the present investigation, investment casting (IC) has been combined with the electromagnetic stirring (EMS) process. The process parameters are chosen on the basis of literature review on IC and EMS processes and these parameters are shell preheat temperature, stirring current, stirring time and pouring temperature. The responses are linear shrinkage, volumetric shrinkage and tensile strength of the investment cast parts. The experiments were conducted as per Taguchi's L9 orthogonal array (OA). As the optimal condition determined for each response was different, grey-fuzzy method was used to combine individual objective functions into a single objective function so as to form a common optimal setting for all the chosen responses. Further, confirmative experiments were done at the obtained common optimal condition to validate the adopted approach in enhancing the quality of the investment cast parts.