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Microstructure of grey cast iron EN GJL-300 after cast to graphite mould (sample I): measurement field 3
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![Fig. 1. Diagram of electromagnetic field influence on the liquid metal [3]](profile/Wrobel-Tomasz/publication/38107002/figure/fig8/AS:668543389536262@1536404573340/Diagram-of-electromagnetic-field-influence-on-the-liquid-metal-3_Q320.jpg)
Purpose: The first aim of investigations was the reduction of grain size and unification of structure for pure Al casting by introduction of small amount of inoculant (less than obligatory standard PN-EN 573-3, which concerning about aluminium purity) and with electromagnetic field. The second aim was to determination of electromagnetic field influ...
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Citations
... Its principle is based on the application of a system of two fields: an electric and a magnetic one. These fields exhibit a mutual relationship described by the Maxwell equations [20]. ...
... The induction coil, powered by electrical current (I 0 ), generates an electromagnetic field that interacts with the solidifying metal at the mould. Hence, this electromagnetic field induces a local electromotive force (E m ) with a magnitude dependent on the local speed of the liquid metal (V) and magnetic induction (B) [20]: ...
... This vector product is a result of the interaction between the magnetic field lines and the current flow of the liquid metal. Consequently, an eddy current (I) is induced in the liquid metal (conductor) [20]: ...
The effect of the application of a rotating magnetic field on the average grain size of IN718 castings was experimentally studied. For the purpose, four parts were produced by investment casting and characterized. The first casting was produced without application of RMF for comparison. The remaining ones were submitted to different RMF frequencies for 15 min and subsequently to the pouring of the nickel-based superalloy. In these three castings, the RMF frequencies applied were, respectively, 15 Hz, 75 Hz and 150 Hz. All the other process parameters were kept constant during the execution of the experimental procedure. The average grain size of the samples was determined according to the ASTM E112-13 standard, using intercept methods. Macro hardness measurements, tensile testing and SEM-EDS analysis were conducted in order to evaluate the casting’s mechanical properties and microstructures. The results demonstrate a noticeable grain size reduction in the samples submitted to rotating magnetic field. An average grain area reduction, greater than 96%, was achieved in the castings where RMF frequencies of 75 Hz and 150 Hz were applied. The application of RMF also caused a morphological change in the casting’s dendrites from cellular to almost equiaxed. Additionally, it originated the decrease of the size and amount of needle-like δ phase. Regarding mechanical properties of the cast parts, no major differences were verified.
... Generally, the different numerical method of the temperature field simulation were applied in the these models, [6], [12], [14], [17], [19], [21]. Particularly some attempts were made to describe the difference between columnar and equiaxed grains creation, [7]- [11], [13], [15]- [16], [18], [20], [22]. In the current model the temperature field is calculated and transformed into thermal gradient field. ...
An innovative method for determining the structural zones in the large static steel ingots has been described. It is based on the mathematical interpretation of some functions obtained due to simulation of temperature field and thermal gradient field for solidifying massive ingot. The method is associated with the extrema of an analyzed function and with its points of inflection. Particularly, the CET transformation is predicted as a time-consuming transition from the columnar- into equiaxed structure. The equations dealing with heat transfer balance for the continuous casting are presented and used for the simulation of temperature field in the solidifying virtual static brass ingot. The developed method for the prediction of structural zones formation is applied to determine these zones in the solidifying brass static ingot. Some differences / similarities between structure formation during solidification of the steel static ingot and virtual brass static ingot are studied. The developed method allows to predict the following structural zones: fine columnar grains zone, (FC), columnar grains zone, (C), equiaxed grains zone, (E). The FCCT-transformation and CET-transformation are forecast as sharp transitions of the analyzed structures. Similarities between steel static ingot morphology and that predicted for the virtual brass static ingot are described.
... Examples of the charging process of the capacitor bank, and the pulse generated to the coil are shown in figure 1a and b. Through the induction coil (45 turns and 120 mm height), pulsed Lorentz forces are generated into the alloy during solidification process as schematically shown in figure 1(b) [14][15][16], and the Lorentz force vector points towards the centre of the coil. ...
A programmable electro-magnetic pulse (PEMP) apparatus has been designed and made, and used to study the effect of different pulse amplitude and frequencies on the solidification microstructure. The measured magnetic fluxes agree well with the simulated fluxes using finite element method. The solidification microstructure of a Sn-18%wtPb was studied using different pulse amplitudes and frequencies. It was found that higher pulse amplitude and frequency lead to more grain refinement.
... Mid-envelope seems to be a kind of an interconnection, [14][15][16][17][18][19][20], which could be a product of a diffusional reaction between c o pper, and some elements f r om the main envelope. ...
... Time a n d temperature promote the formation o f t h e intermediate layer located between envelope and droplet itself. In this unusual situation, a kind of interconnection is formed [14][15][16][17][18][19][20]. ...
Purpose: A suspension of copper droplets in the slag coming from the direct-to-blister process was subjected to the treatment analogous to that usually applied to the electric arcfurnace process. In particular, recently patented by authors, complex reagent was applied and verified. Design/methodology/approach: The suspension was subjected to coagulation and solidification. Both processes were studied, independently. The suspension of droplets was treated not only by the recently patented complex reagent but by the CaO – industrial compound (in the amount of 5 %wt.) as well, to make comparison between both substances effectiveness. Findings: The observation was focused on the behavior of droplets to conclude whether the droplets are settled on the crucible bottom due to the effect of gravity or pushed to the liquid slag’s surface due to buoyancy force influence. In the case of the patented reagent application, the coagulation mainly was completed by the droplets’ settlement on the crucible bottom. The treatment performed with the use of the CaO – compound promoted the influence of buoyancy force. The coagulated copper droplets were pushed to the liquid slag’s surface. Research limitations/implications: Rest reagents known in the industry practice will be subjected to the analogous analysis in order to make further comparison with the effect of the patented chemical. Practical implications: Conclusion from the performed experiment made in the crucible (laboratory scale) allow to suggest how to improve not only the semi- or fully industrial directto- blister technology but the treatment of the slag in the electric arc-furnace as well.
... If the solidification structure is equiaxial, the solid-liquid blending remains fluid from 20 % to 30 % of the solid. In addition, the fluid movement provokes the fragmentation of the dendrites and the multiplication of the equiaxial grains, making possible the columnar-equiaxial transition and a substantial reduction in the grain size and refinement of grains [15][16][17][18][19][20]. ...
This work has the objective of evaluating the effect of electromagnetic stirring (EMS) used in continuous ingot (CI) in the mechanical and metallurgical properties of hot forged flanges of AISI 1025 steel. Three conditions of raw material were supplied and compared before the forging process: one from CI using EMS; the other, prevenient from CI without EMS, and the last, with CI without EMS, and, subsequently, submitted to hot rolling process. Billets were extracted from these raw materials to manufacture connection flanges through hot forging. To evaluate the mechanical properties of the forged pieces, tension, hardness and impact tests were done, and the microstructure was observed by optical microscopy. Macrographs and penetrating liquid non-destructive testing were also done. The results of the above-mentioned tests showed proximate mechanical and metallurgical properties approved by the reference norm (ASTM A105) of the flanges manufactured with the raw materials obtained by CI with EMS and hot rolling.
... The stirring of the metal allows to smooth the S/L interface, to refine grains, to homogenize ingot properties and to destruct partially dendrites under the conditions of temperature fluctuations and energy transfer. Moreover, the stirring contributes to the uniform distribution of impurities and crystal grains transported by the flow, which also improves the properties of the ingot [7]. The velocity field and the position of the L/S interface were determined using the Ultrasonic Doppler Velocimeter (UDV, DOP2000, Signal Processing). ...
The flow and crystallization processes in a thin layer of liquid metal are investigated. The flow in the layer is induced by an electromagnetic force. The inductor with a ferromagnetic C-core generates an alternating magnetic field in the layer. The flow makes it possible to stir the molten metal at the solidification stage. In this study, the Ultrasonic Doppler Velocimeter was used to measure the solidification front movement in a thin layer of liquid gallium. The obtained results have shown that the Ultrasonic Doppler Velocimeter can be effectively used to study the process of crystallization in liquid metals.
... Skeleton casting macrostructure can be shaped in many ways by choosing an appropriate material of cores and manufacturing technologies. Important factor, that puts foundry techniques over the other technologies of periodic cellular materials is ability to select mechanical properties by changing the microstructure of an alloy from which the casting is made [14,15,[19][20][21][22][23]. The influence on the microstructure of the skeleton casting can be implemented by choosing the thermal properties, mainly thermal conductivity factor, of mould and core materials [16]. ...
Skeleton castings macrostructure can be shaped in many ways, by choosing an appropriate material of cores and manufacturing technologies. Important factor, which puts foundry techniques over the other technologies of periodic cellular materials, is ability to adjust mechanical properties by changing the microstructure of an alloy from which the casting is made. The influence on the microstructure of the skeleton casting can be implemented by choosing the thermal properties, mainly thermal conductivity factor, of mould and core materials. Macro- and microstructure of skeleton castings with octahedron elementary cells was presented in this paper. The analysis concerns the differences in morphology of eutectic silicone depending on the location of measurements cross sections areas. The use of thermo-insulating material with appropriate properties assures correct fill of mould cavity and homogeneous microstructure on whole volume of skeleton casting. The selection of technological parameters of the casting process if very important as well.
... Continuous casting process covers many complex phenomena including turbulent multiphase fluid flow, heat transfer and solidification. Convection of molten metal in the crystallizer, and thus shifting and changing of the solid / liquid interface shape have a major impact on the quality of the ingot [2,6,7,14,15]. Implementation of the work required to set out for a series of simulations involving the following steps: 1. Designing of the crystallizer model in ANSYS Fluent 12 on the basis of actual mold used in the research: ...
Cast ingot pulling speed is significantly affecting the nature of the resulting structure and the quality of the outer surface of the ingot. By introducing a variable algorithm for extraction of the ingot we may to some extent control the shape and location of the solid / liquid interface and temperature field in the cross-section of the ingot. The shape of the crystallization front, as well as its position relative to mold plays an important role in the process of continuous casting ingots of grey iron and affects the structure of the casting. In order to verify the impact of an algorithm on the shape and the location of solid / liquid interface, a number of simulations in ANSYS Fluent 12 were made, for determining the shape of crystallization front and temperature distribution on the cross-section of the ingot.
... Then important is other method of inoculation, which consists in influence of electromagnetic field on liquid metal in time of its solidification in mould [3,[13][14][15]. ...
... Forced liquid metal movement influences in diversified way on changes in structure of casting i.e. by changes of thermal and concentration conditions on crystallization front, which decrease or completely stops the velocity of columnar crystals growth and by [3,[13][14][15]: ...
Purpose: In paper is presented problem concerning inoculation of pure aluminium primary structure, which is realized mainly by intensification of liquid metal movement in mould by use of electromagnetic field.Design/methodology/approach: In aim of realization of forced movement during the crystallization of liquid metal was used rotate electromagnetic field, which is generated by induction coil fed with frequency of supply current from 25 to 100Hz. Effect of structure refinement obtained by influence of electromagnetic field was compared with refinement obtained by use of traditional inoculation, which consists in introducing of additions in form of titanium and boron to metal bath.Findings: The results of investigations and their analysis show possibility of effective refinement of pure aluminium primary structure, only with use of electromagnetic field.Research limitations/implications: I further research, authors of this paper are going to application of introduced method of Al casting with use of electromagnetic field in continuous casting stand.Practical implications: The work presents refinement of structure method which are particularly important in continuous and semi – continuous casting where products are used for plastic forming.Originality/value: The value of this paper resides in new effective method of inoculation of pure Al, which was realized only by use of electromagnetic field.
... For example in Fig. 2 is presented influence of casting in rotate electromagnetic field on unification and reduction of grain size in macrostructure of pure aluminium of type EN AW-Al99.5 ingots. Macrostructure of pure aluminium of type EN AW-Al99,5 ingot in initial state (a), and after casting with influence of rotate electromagnetic field (b) [11] In contrast, the papers [14,15] present the possibility of influence of the electromagnetic field on the solidifying metal to unification the structure of grey cast iron. It is anticipated that this procedure will allow to obtain more favorable properties as compared to grey cast iron without forced convection at the time of its solidification in continuous casting mould. ...
Purpose: The main aim of investigations was the unification of flake graphite morphology in cast iron ingots in conditions of forced convection of liquid metal in the continuous casting mould, which contains electromagnetic stirrer.Design/methodology/approach: To investigations of grey cast iron ingots were used laboratory stand of continuous casting, which contains continuous casting mould with inductor of rotate electromagnetic field.To investigations were made metallographic researches on scanning electron microscope and investigations of usable properties i.e. measurements of hardness and machinability.Findings: The results of investigations and their analysis show possibility of unification of flake graphite morphology in cast iron structure, and distribution of hardness on cross-section of ingot and its machinability.Research limitations/implications: In further research, authors of this paper are going to application of introduced method of continuous casting with use of electromagnetic field in industrial tests.Practical implications: The work presents method of unification of structure and properties, which are particularly important in continuous casting. Uniform morphology of flake graphite in structure of cast iron ingots for automobile industry is very important in viewpoint of machinability.Originality/value: Contributes to improvement in quality of grey cast iron continuous casted ingots.
