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EN
Convection caused by gravity and forced flow are present during casting. The effect of forced convection generated by a rotating magnetic field on the microstructure and precipitating phases in eutectic and hypoeutectic AlSiMn alloys was studied in solidification by a low cooling rate and low temperature gradient. The chemical composition of alloys was selected to allow joint growth or independent growth of occurring α-Al, α-Al15Si2Mn4 phases and Al-Si eutectics. Electromagnetic stirring caused instead of equiaxed dendrites mainly rosettes, changed the AlSi eutectic spacing, decreased the specific surface Sv and increased secondary dendrite arm spacing λ2 of α-Al, and modified the solidification time. Forced flow caused complex modification of pre-eutectic and inter-eutectic Mn-phases (Al15Si2Mn4) depending on the alloy composition. By high Mn content, in eutectic and hypoeutectic alloys, stirring caused reduction in the number density and a decrease in the overall dimension of pre-eutectic Mn-phases. Also across cylindrical sample, specific location of occurring phases by stirring was observed. No separation effect of Mn-phases by melt flow was observed. The study provided an understanding of the forced convection effect on individual precipitates and gave insight of what modifications can occur in the microstructure of castings made of technical alloys with complex composition.
EN
During mold filling and casting solidification, melt flow caused by gravity is present. Otherwise, forced flow may be a method applied for casting properties improvement. The flow effect generated by an electromagnetic field on the growing phases and a whole microstructure in Al-Si-Mn alloys was studied by slow solidification conditions. The hypereutectic and eutectic alloys were chosen to allow independent growth or joint growth of forming: Si crystals, Mn-rich α-Al15Si2Mn4 phases and Al-Si eutectics. In eutectic alloys, where Mn-phases precipitate as first and only one till solidus temperature, flow decreased number density of pre-eutectic α-Al15Si2Mn4. In the hypereutectic alloys, where Mn-phases grow in common with Si crystals, forced convection increased the overall dimension, decreased number density of pre-eutectic Mn phases and strengthened the tendency to growth in the outside of the sample. In the alloys, where Si crystals grow as first, stirring reduce number density of Si and moved them into thin layer outside cylindrical sample. Also by joint growth of Si crystals and Mn-phases, in hypereutectic Mn/Si alloy, flow moved Si crystals outside, reduced number density and increased the dimension of crystals. Stirring changed also AlSi eutectic spacing, specific surface Sv of α-Al and secondary dendrite arm spacing λ2. The results gave insight of what transformation under stirring take place in simple Al-Si-Mn alloys, and helps to understand what modifications in technical alloys may occur, that finally lead to changes in castings microstructure and properties. The possibility to control dimension, number density and position of Mn-phases and Si crystals is completely new and may help by metallurgical processes, continuous casting of billets and in the production of Si for the solar photovoltaic industry.
EN
Electromagnetic stirrer generates swirling fluid flow, boosts the mixing of molten steel near the solidification front and enhances the quality of the continuously cast products. In the present investigation, attention is paid towards studying the effect of in-mold electromagnetic stirring on fluid flow and solidification. A three-dimensional coupled mathematical model of solidification and magnetohydrodynamics has been established for billet caster mold. The alternating magnetic field is applied to the solidification model where fluid flow, heat transfer, and electromagnetic equations are solved simultaneously. It has been found that an increase in field frequency decreases the length of stirring and the liquid fraction of the steel at the center of the mold exit. Tangential velocity near the solidification front increases with the magnetic field frequency or flux density, due to which, a break in solidified shell near stirrer position is predicted whose width increases accordingly.
EN
The paper presents the research results of horizontal continuous casting of ingots of aluminium alloy containing 2% wt. silicon (AlSi2). Together with the casting velocity (velocity of ingot movement) we considered the influence of electromagnetic stirring in the area of the continuous casting mould on refinement of the ingot’s primary structure and their selected mechanical properties, i.e. tensile strength, yield strength, hardness and elongation. The effect of primary structure refinement and mechanical properties obtained by electromagnetic stirring was compared with refinement obtained by using traditional inoculation, which consists in introducing additives, i.e. Ti, B and Sr, to the metal bath. On the basis of the obtained results we confirmed that inoculation done by electromagnetic stirring in the range of the continuous casting mould guarantees improved mechanical properties and also decreases the negative influence of casting velocity, thus increasing the structure of AlSi2 continuous ingots.
PL
Własności mechaniczne wyrobów ze stopów aluminium zależą zarówno od gatunku stopu aluminium, co jest związane bezpośrednio z obecnością dodatków stopowych w strukturze metalu bazowego, jak i stanu materiału. Innym czynnikiem wpływającym na te własności oraz podatność materiału do przetwarzania metodami przeróbki plastycznej na zimno i na gorąco jest stopień rozdrobnienia struktury. Najbardziej rozpowszechnioną metodą rozdrobnienia struktury stosowaną przemysłowo jest modyfikacja chemiczna z wykorzystaniem zaprawy AlTi5B1. Alternatywą dla tej metody, również skutkującą modyfikacją struktury wewnętrznej materiału, może być mieszanie elektromagnetyczne w strefie przykrystalicznej. Zastosowanie tej metody pozwala na uzyskanie struktury zarówno drobnoziarnistej, jak i jednorodnej oraz prowadzi do zmniejszenia segregacji dodatków stopowych. W ramach niniejszej pracy dokonano analizy wpływu elektromagnetycznej modyfikacji struktury stopów EN AW 6060 otrzymanych w linii ciągłego odlewania w połączeniu z klasyczną modyfikacją chemiczna na efekt rozdrobnienia struktury oraz jej jednorodność. Dodatkowo dokonano szerokiej analizy własności mechanicznych, elektrycznych oraz fizycznych otrzymanych materiałów.
EN
Mechanical properties of products made from aluminum alloys depends both on the grade of aluminum alloy (which it is directly connected with the presence of alloy additions in the aluminum structure) and also on the temper of the material. Fineness of metal structure is another factor which has an influence on this properties as well as it influence metal susceptibility to hot and cold metal forming processes. The most commonly used industrial method of structure refinement is chemical modification with the use of AlTi5B1 master alloy. Alternative method which also allows to modify the internal structure of metal is electromagnetic stirring within crystallization zone during casting process. Use of this method allows to obtain fine grained and homogenous structure and also results in the decrease of alloy additions segregation. In this paper, the influence of electromagnetic stirring combined with classic chemical modification on EN-AW 6060 aluminum alloys structure was analyzed as a part of studies on continuous casting process. In addition, mechanical, electrical and physical properties of obtained materials were studied and presented in the paper.
EN
In paper is presented results of studies concerning ingot of Al with a purity of 99.5% cast with use of stand of horizontal continuous casting. Mainly together with casting velocity was considered influence of electromagnetic stirrer, which was placed in continuous casting mould on refinement of ingots structure and theirs usability to plastic deformation. Effect of structure refinement and usability to plastic deformation obtained by influence of electromagnetic stirring was compared with refinement obtained by use of traditional inoculation, which consists in introducing of additives i.e. Ti and B to metal bath. On the basis of obtained results was affirmed that inoculation realized by electromagnetic stirring in range of continuous casting mould guarantees improvement in structure refinement and usability to rolling of pure Al continuous ingots.
PL
Referat przedstawia koncepcję oraz prototyp układu do eksperymentalnego wyznaczenia wielkości charakteryzujących ruch płynnego metalu wywołany mieszaniem elektromagnetycznym w procesie odlewania ciągłego aluminium. Mieszanie metalu w trakcie krystalizacji ma istotny pozytywny wpływ na strukturę odlewu. Badania mają na celu uzyskanie zależności eksperymentalnych, które umożliwią weryfikację wyników uzyskanych w wyniku modelowania procesu odlewania.
XX
The paper presents a concept and a prototype experimental system for determination of the velocity of liquid metal caused by electromagnetic stirring in continuous casting process of aluminum. Stirring during the crystallization of a metal has a significant positive impact on the structure of the casting. The concept is based on the observation that the vertical magnetic field results in a conical uplift of a liquid metal. The height of the cone depends on the velocity at which the metal is stirred by a magnetic field. The paper presents the design of a measuring system for determining the height of the liquid metal cone. It also presents a prototype built and the results obtained. The prototype was constructed to verify the proposed concept and to perform practical tests showing if the results could be useful. The purpose of the research is to obtain experimental dependencies that enable the verification of the results obtained in the modeling of the casting process.
EN
The paper presents an attempt of modelling liquid steel motion triggered off by electromagnetic stirring. Steel viscosity was calculated on the basis of temperature field determined with the use of stationary heat conduction equation. Velocity field was determined using Navier-Stokes equations and stream continuity equation. Solution was obtained using the finite element method. The developed model allows to carry out quick simulating calculations of fluid flow. Stationary solution was employed, and this allowed to reduce computation time substantially.
PL
W pracy podjęto próbę modelowania ruchu ciekłej stali wywołanej mieszaniem elektromagnetycznym. Lepkość stali obliczano na podstawie pola temperatury wyznaczonego ze stacjonarnego równania przewodzenia ciepła. Pole prędkości wyznaczono korzystając z równań Naviera-Stokesa i równania ciągłości strugi. Rozwiązanie uzyskano metodą elementów skończonych. Opracowany model pozwala na wykonywanie szybkich obliczeń symulacyjnych ruchów ciekłej stali. Zastosowano rozwiązanie stacjonarne, co umożliwiło istotne skrócenie czasu obliczeń.
EN
The paper presents modification of primary structure of Al 99,5% and 99,8% purity and AlSi2 alloy by electromagnetic stirring of liquid metal within foundry mould. The movement of solidifying liquid metal within the mould was forced by horizontal electromagnetic field produced by the induction coil (stirrer), supplied by current of elevated frequency. The structure refinement obtained by electromagnetic stirring was compared with refinement obtained by traditional modification, i.e. by introducing Ti, B, C and Sr modifying additives into melt. The results of studies show possibility of effective primary structure refinement of pure Al and selected Al-Si alloy by using only horizontal electromagnetic field, without necessity of Ti, B and C additives application.
PL
W pracy przedstawiono problematykę modyfikacji struktury Al o czystości 99,5% i 99,8% oraz stopu AlSi2, realizowanej głównie poprzez intensyfikacje ruchu ciekłego metalu w formie. W celu realizacji wymuszonego ruchu krzepnącego metalu zastosowano pole elektromagnetyczne wytwarzane przez cewkę (mieszadło) zasilane prądem o podwyższonej częstotliwości. Efekt rozdrobnienia struktury uzyskany w wyniku użycia mieszania elektromagnetycznego był porównywany z możliwym do otrzymania przy użyciu tradycyjnej modyfikacji, która polega na wprowadzeniu do ciekłego metalu dodatków tytanu, boru, węgla i strontu. Wyniki badań oraz ich analizą pokazały, że istnieje możliwość skutecznego rozdrobnienia struktury pierwotnej czystego Al i wybranego stopu Al-Si tylko przy użyciu mieszania elektromagnetycznego bez konieczności stosowania dodatków modyfikujacych tj. Ti, B i C.
EN
In paper is presented idea of construction and influence of selected parts of stand of horizontal continuous casting on quality of pure Al and AlSi2 alloy ingots. The main parts of the made stand belong to induction furnace, which is also tundish, water cooled continuous casting mould, system of recooling, system of continuous ingot drawing and cutting. Mainly was considered influence of electromagnetic stirrer, which was placed in continuous casting mould on refinement of ingots structure. Effect of structure refinement obtained by influence of electromagnetic stirring was compared with refinement obtained by use of traditional inoculation, which consists in introducing of additives i.e. Ti and B to metal bath. The results of studies show possibility of effective refinement of Al and AlSi2 alloy primary structure, only with use of horizontal electromagnetic field and without necessity of application of inoculants. This method of inoculation is important, because inoculants decrease the degree of purity and electrical conductivity of pure aluminum and moreover are reason of point cracks formation during rolling of ingots.
EN
Purpose: The aim of the paper is to investigate practical possibilities of the strand stirrer (S-EMS) for the improvement of inner quality and central segregation in high carbon billets. An optimal S-EMS setting was proposed for the billet caster producing billets 150x150 mm. Design/methodology/approach: Impact of different S-EMS settings on central segregation and inner quality of as-cast billets was investigated. A set of longitudinal and transverse samples were analysed including evaluation of baumann prints and central segregation by means of LECO method. Samples of wires for segregation survey in rolled products were picked up as well. Findings: It was observed that application of the strand stirrer (S-EMS) is capable to suppress central segregation. However, its impact is visible just to a certain stirring level. Subsequent increasing of stirring intensity does not cause further improvement of segregation in the analyzed central part. On the contrary, stronger white band can be seen in the solidification line. Moreover, concentration gradient between the central part and surrounding ring of negative central segregation is lowered. These two effects can play a significant role in the evaluation of segregation level in rolled wires. Research limitations/implications: Analysis of central segregation in a lower size than used 6 mm. Practical implications: Optimal S-EMS setting seems to be 300 A/14 Hz. Originality/value: Impact of S-EMS setting on changes in central segregation of as-cast billets, relationship between central segregation level in wires and cast structure.
PL
W artykule przedstawiono model matematyczny ciągłego odlewania stali z mieszaniem elektromagnetycznym. Następnie przeprowadzono analizę wpływu intensywności mieszania elektromagnetycznego na prędkość metalu wewnątrz ciekłej fazy.
EN
The paper presents the mathematical model of the process of continuous casting of steel with electromagnetic stirring. Then the analysis of the impact of the intensity of electromagnetic stirring on the velocity fields in the liquid core was presented.
13
Content available remote Analiza polowa cieplna i elektromagnetyczna procesu ciągłego odlewania żeliwa
PL
Celem artykułu jest wyznaczenie strefy krystalizacji żeliwa oraz sił generowanych elektromagnetycznie, działających na żeliwo w strefie krystalizacji w procesie odlewania ciągłego żeliwa. Odlewanie ciągłe żeliwa wymaga zapewnienia podczas krystalizacji odpowiednich rozkładów gradientów temperatury w celu uzyskania właściwej struktury odlewu. Badania są prowadzone na podstawie metody elementów skończonych (MES) i oprogramowania ANSYS. Analizę cieplną oraz analizę elektromagnetyczną sił oddziałujących na żeliwo przebadano w dwóch różnych rodzajach niezależnych modeli komputerowych. Wyznaczono strefę krystalizacji oraz rozkłady sił elektromagnetycznych w żeliwie.
EN
The aim of the paper is to determine crystallization zone and forces generated by the electromagnetic field acting on cast iron during crystallization in continuous casting process. Proper distributions of temperature gradients are needed during continuous casting process to receive the proper cast iron structure. Analysis is carried out using the finite element method (FEM) and ANSYS software. The thermal and electromagnetic analysis of force interactions on cast iron was carried out using two different independent computational models. The crystallization zone and distribution of magnetic forces in cast iron were determined.
EN
The paper presents the results of numerical simulation of the process of continuous casting with electromagnetic stirring and an analysis of the influence of the intensity of electromagnetic stirring on the shell thickness and the metallurgical length.
PL
W artykule przedstawiono wyniki badań numerycznych procesu ciągłego odlewania stali z mieszaniem elektromagnetycznym. Określono wpływ intensywności mieszania elektromagnetycznego na grubość naskórka oraz długość metalurgiczną.
15
Content available remote A concast billet caster and electromagnetic stirring of the melt
EN
Electromagnetic stirring (EMS) suppresses the growth of columnar crystals of billets and reduces the tendency to cracking during casting and at low temperatures. A caster was used for the testing of two induction stirrers – one on the actual mould and the other beneath the mould – to determine the effect of EMS on the formation of the structure of non-alloy steel. As part of these tests, certain parts of the billets had been cast without the use of stirrers and other parts underwent alternate switching on and off of the stirrers for as many as nine combinations of modes. Samples were taken from the sections of these billets, fine-ground and etched in order to make the dendritic structure visible. The mode with the highest effi ciency was when both stirrers ran simultaneously. The growth of the columnar crystals, which pointed inward, was limited to 1/4 -to- 1/3 of the length of the case when there was no stirring. Experimental research was also confronted with results acquired from the application of the models of the temperature field and chemical heterogeneity and the physical-similarity theory. Statistical monitoring of the quality of concast billets has proven that stirring significantly reduces the occurrence of defects – in this case cracks.
16
Content available remote Weak conducting material melt flow in crossed EM fields
EN
New equipment for electromagnetic processing of weak conducting material melts was numerically investigated. Significance of different effects and physical phenomena was evaluated. Complicated melt flow structure was obtained at specific equipment parameters.
PL
Nowe wyposażenie do elektromagnetycznego przetwarzania kąpieli materiałów słabo przewodzących zostało przebadane w drodze analizy numerycznej. Ważność różnych efektów i zjawisk fizycznych została oceniona. Dla konkretnych parametrów urządzenia otrzymano skomplikowana strukturę przepływu kąpieli.
PL
W pracy dokonano przeglądu urządzeń elektromagnetycznych do transportu i mieszania ciekłych metali skupiając się na przykładzie urządzeń zbudowanych w Katedrze Elektrotechnologii Politechniki Śląskiej. Omówiono metody obliczania takich urządzeń. Obliczono rozkład siły Lorentza w kanale dozownika elektrodynamicznego do ciekłego cynku.
EN
The paper presents a review of electromagnetic devices for transportation and stirring of liquid metals with a special emphasis at devices built in Department of Electrotechnology of the Silesian University of Technology. Methods of calculations for such devices were discussed. Distribution of Lorentz forces in a channel of an electrodynamic feeder with liquid metal were calculated.
PL
W pracy dokonano krótkiego przeglądu urządzeń elektromagnetycznych do transportu i mieszania ciekłych metali skupiając się na przykładzie urządzeń zbudowanych i zaprojektowanych w Katedrze Elektrotechnologii Politechniki Śląskiej. Omówiono metody obliczania takich urządzeń. Obliczono rozkład siły Lorentza w kanale dozownika elektrodynamicznego do ciekłego cynku. NakreśIono plan dalszych prac.
EN
The paper presents a short review of electromagnetic devices for transportation and stirring of liquid metals putting a special emphasis at devices built in Chair of Electrotechnology of the Silesian University of Technology. Method of calculations of such devices were discussed. Distribution of Lorentz forces in a channel of an electrodynamic feeder for liquid metal was calculated. Overall plan offitrther activities in the area was discussed.
PL
W artykule przedstawiono rezultaty kompleksowej analizy procesu mieszania elektromagnetycznego, obejmującej rozwiązanie trzech zagadnień: elektromagnetycznego, termokinetycznego i hydrodynamicznego. Przyjęto, że analizowane pola fizyczne nie są sprzężone. Wyznaczono m.in. gęstości sił elektromagnetycznych działających na ciekły rdzeń wlewka, grubość warstwy zakrzepniętej oraz rozkłady prędkości mieszanego metalu. Do obliczeń wykorzystano własne programy komputerowe oraz programy komercyjne: Calcosoft i Fluent.
EN
The paper presents the results of complex analysis of electromagnetic stirring process, including solution to the following three problems: electromagnetic, thermokinetic and hydrodynamic. It has been assumed that analysed physical fields are not coupled. Among others, electromagnetic forces densities influencing liquid ingot core, solidified layer thickness and velocity distributions of stirred metal were determined. Author's computer programmes and commercial computer programmes Calcosoft and Fluent were used for the calculations.
PL
W pracy przedstawiono wyniki obliczeń numerycznych dotyczących początkowej fazy procesu krzepnięcia wlewka w strefie krystalizatora podczas ciągłego odlewania stali. Symulacje komputerowe wykonano w programie Fluent z zastosowaniem modułu magnetohydrodynamicznego (MHD) dla warunków odlewania uwzględniających działanie mieszadła elektromagnetycznego typu M-EMS (Mould Electromagnetic Stirrer) umieszczonego wokół mieszadła. Dokonano oceny wpływu zastosowania mieszania elektromagnetycznego w modelowaniu matematycznym rozkładu wektorów prędkości ciekłej stali w tej strefie. Stosowanie dodatkowego modułu w programie Fluent znacznie poszerza zakres prowadzonych obliczeń, przybliżając tym samym otrzymywane wyniki badań modelowych do realnych warunków przemysłowych ciągłego odlewania stali.
EN
The article presents the results of the numerical computations of the initial phase of solidification of ingot in mould zone during continuous steel casting process. Computer simulations were carried out in the Fluent program with the magnetohydrodynamic module (MHD) in mathematical modelling for conditions of the CC process with electromagnetic stirring. Influence of electromagnetic stirring on distribution of liquid steel velocity vectors in the mould zone was carried out. This additional module in Fluent programme increases the range of computations and brings closer the results of modelling to the real industrial conditions of continuous casting process.
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