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EN
An overview of the bibliography regarding the connection of knowledge about precious metal alloys and aspects of the use of computer aided technologies to the optimization of the jewelry casting processes is presented. An analysis of the usability of selected CAx systems was made: 1) for spatial design, called Rhinoceros 6 and 2) CAE system: NovaFlow & Solid (NF&S). The authors describe own research including data acquisition and evaluation of temperature variations during solidification of the selected Au-Ag-Cu alloy, with the identification of the phase transformations of this alloy. The intensity of heat exchange was changed (cooling of specimens under ambient temperature conditions – "normal" intensity and with the furnace – very slow cooling). The problem of completing the simulation database was pointed out and analyzed. Examples of simulations of casting selected jewelry (ring and signet) were given and compared with the result of the experiment realized in real conditions. It was confirmed that the optimization by combining experimental and simulation studies allows for the acquisition of new knowledge, and also facilitates the creation of new artistic designs of jewelry as well as performing the feasibility check, and then optimizing the chosen technology.
PL
W artykule przedstawiono główne założenia modelu matematycznego przepływu ciekłej stali sprzężonego z modelem krzepnięcia. Prezentowane rozwiązanie bazuje na metodzie hydrodynamiki cząstek rozmytych i stanowi pierwszy etap prac rozwojowych zmierzających do opracowania kompleksowego modelu odkształcania stali w stanie półciekłym. Docelowo opracowany model numeryczny umożliwi symulację odkształcania stali w warunkach współistnienia fazy ciekłej i stałej, z uwzględnieniem lokalnych przepływów krzepnącej stali w obrębie zestalonego szkieletu fazy stałej. Implementacja numeryczna modułu obliczeniowego hydrodynamiki cząstek rozmytych realizowana jest w ramach rozwijanego od kilkunastu lat autorskiego pakietu DEFFEM 3D. Uzupełnienie pracy stanowią przykładowe wyniki symulacji testowych wskazujących na poprawność przyjętych założeń modelowych.
EN
The article presents the main assumptions of the mathematical model of liquid steel flow coupled with the solidification model. The presented solution is based on the smoothed particle hydrodynamics method and is the first stage of development works aimed at developing a comprehensive model of steel deformation in the semi-solid state. Ultimately developed numerical model will enable simulation of steel deformation in the semi-solid state, taking into account local flows of solidifying steel within a solidified solid phase skeleton. The numerical implementation of the SPH solver is carried out as part of the DEFFEM 3D package being developed for over a dozen years. The supplements to the work are exemplary results of test simulations indicating the correctness of the adopted model assumptions.
EN
There has been a growing interest in the peritectic due to increasing productivity, quality, and alloy development. Differential scanning calorimetry (DSC) has traditionally been used to study steel solidification but suffers significant limitations when measuring the solidus and peritectic. This work covers a new thermal analysis system that can characterize the peritectic reaction. Heats of AISI/SAE 1030 and 4130 steel were poured to provide some benchmarking of this new technique. The peritectic was detected and the reaction temperature measured. Measurements agree reasonably well with reference information. A review of the literature and thermodynamic calculations did find some disagreement on the exact temperatures for the peritectic and solidus. Some of this difference appears to be related to the experimental techniques employed. It was determined that the system developed accurately indicates these reaction temperatures. The system provides a unique method for examining steel solidification that can be employed on the melt deck.
EN
The article presents an integrated analytical and measurement system for evaluation of the properties of cast metals and alloys. The presented platform is an extension of the SLAG - PROP application with new modules, which allow to use information on metallurgical processes in an even more effective way, as well as to evaluate the finished product. In addition, the construction of a measuring station for the analysis of thermal processes taking place in a metal bath allows for precise observation of phenomena together with their appropriate interpretation. The article presents not only the cooling curves of certain copper alloys. The analysis also covered mechanical properties related to hardness, finished products depending on the mold in which the products were cast. In the literature one can find information about the mechanical properties of products in the improved state, usually after plastic or thermal treatment, omitting their properties obtained as a result of a naturally made casting. The article also presents the method of placing information in the database using a convenient graphical tool.
EN
Purpose: During weld metal structure formation the possibility of impact on its mechanical properties are much more limited in comparison with metallurgy and technology of steel production. Adding of the inoculants to the welding pool is one of the promising methods of influencing the structure and mechanical properties of the weld metal. Design/methodology/approach: Cellular automata (CA) with additions of finite difference method (FDM) is one of the best ways to simulate dendritic growth process with the surfaceactive inoculants. It`s easy to add new rules of interaction between the inoculants and dendrite surface to the cellular automata model. Findings: It was found that average distance between primary dendrites axis decrease with increase of the inoculants wetting angle by melt iron. Obtained results were confirmed experimentally on weld metal samples that were obtained by the welding of HSLA steels with the surface-active inoculants. Research limitations/implications: The inoculants with size that comparable with cells size of the model (≈0.4 microns) were distributed evenly in computational area. Practical implications: Adding of surface-active inoculants to the melt metal improve structure and mechanical properties of weld metal. Different refractory particles (TiC, TiN, SiC, TiO2, Al2O3 and ZrO2) can be used. Originality/value: Refractory inoculants adding to the melt metal are wide used in metallurgy as crystallization centers and heat absorbers. Inoculants that were added to the welding pool of high-strength low-alloyed (HSLA) steel welds could also influence on crystallization processes of weld metal as surface active particles. In the contact point between the dendrite surface and the surface-active inoculant, a surface energy is change depending of the inoculant surface properties. Different refractory particles (TiC, TiN, SiC, TiO2, Al2O3 and ZrO2) were used.
6
EN
Fe - 4,25% C alloy was directionally solidified with a constant temperature gradient of G = 33,5 K/mm and growth rate of v = 83,3 μm/s (300 mm/h) using a vacuum Bridgman-type crystal growing facility with liquid metal cooling technique. To reveal more detailed microstructure, the deep etching was made. This was obtained in the process of electrolytic dissolution. The microstructure of the sample was examined on the longitudinal and transverse sections using an Optical Microscope and Scanning Electron Microscope. Using the Electron Backscattered Diffraction technique, phase map and analysis of phase were made. In this paper the analysis of Fe-C alloy eutectic microstructure is presented. Regular eutectic structure was obtained. The fracture surfaces show lamellar structure. Microscopic observation after electrolytic extraction indicates that the grains of longitudinal shape of eutectic cementite have been obtained. These grains are characterized by layered construction with many rounded discontinuities.
EN
Determination of the ferrite content in austenitic steels, which solidified under defined conditions. Ferrite content in austenitic matrix was determined from samples with wall thickness of 60 mm. Measured ferrite contents served to propose the regression equations for the calculation of the ferrite content in steels with Cr content of 18 up to 22 % and Ni of 9 up to 11 %. An additional regression equation was proposed for steels with a higher Ni content. The proposed regression equations have been checked up on the operating melts. In conclusion, the ferrite content in the axis of the casting of wall thickness of 500 mm has been calculated and it was compared to the ferrite determined in the usual way from the cast-on test.
EN
The copper droplets contained in the post-processing liquid slag are subjected to the treatment by the complex reagent. The complex reagent has been recently elaborated and patented in frame of the Grant No. PBS3/A5/45/2015. In particular, the complex reagent is dedicated to the post-processing slags coming from the Smelter and Refinery Plant, Głogów, as a product of the direct-to-blister technology performed in the flash furnace. The recently patented complex reagent effectively assists not only in agglomeration, and coagulation but also in the deposition of the copper droplets at the bottom of crucible / furnace as well. The treatment of the post-processing slags by the complex reagent was performed in the BOLMET S.A. Company as in the industrial conditions which were similar to those usually applied in the KGHM – Polish Copper (Smelter and Refinery Plant, Głogów). The competition between buoyancy force and gravity is studied from the viewpoint of the required deposition of coagulated copper droplets. The applied complex reagent improves sufficiently the surface free energy of the copper droplets. In the result, the mechanical equilibrium between coagulated copper droplets and surrounding liquid slag is properly modified. Finally, sufficiently large copper droplets are subjected to a settlement on the crucible / furnace bottom according to the requirements.
EN
In this paper, the mathematical model and numerical simulations of the molten steel flow by the submerged entry nozzle and the filling process of the continuous casting mould cavity are presented. In the mathematical model, the temperature fields were obtained by solving the energy equation, while the velocity fields were calculated by solving the momentum equations and the continuity equation. These equations contain the turbulent viscosity which is found by solving two additional transport equations for the turbulent kinetic energy and its rate of dissipation. In the numerical simulations, coupling of the thermal and fluid flow phenomena by changes in the thermophysical parameters of alloy depending on the temperature has been taken into consideration. This problem (2D) was solved by using the finite element method. Numerical simulations of filling the continuous casting mould cavity were performed for two variants of liquid metal pouring. The effect of the cases of pouring the continuous casting mould on the velocity fields and the solid phase growth kinetics in the process of filling the continuous casting mould was evaluated as these magnitudes have an influence on the high quality of the continuous cast steel slab.
10
Content available remote Hybrid model of liquid metal flow and solidification
EN
The article presents a hybrid model dedicated to simulations of liquid metal flow and its solidification. The developed solution is a key component of the developed integrated modelling concept, which combines the advantages of physical and computer simulations, while the concept itself is the foundation of a scientific workshop oriented at high-temperature processes (close to solidus lines). Examples of test simulation results are presented, indicating that the adopted model assumptions are correct.
PL
W artykule przedstawiono hybrydowy model dedykowany symulacjom przepływu ciekłego metalu i krzepnięcia. Opracowane rozwiązanie jest kluczowym elementem rozwijanej koncpecji zintegrowanego modelowania łączącego zalety symulacji fizycznej i komputerowej, zaś sama koncepcja stanowi fundament warsztatu naukowego zorientowanego na procesy wysokotemperaturowe (bliskich linii solidus). Przedstawiono przykładowe wyniki symulacji testowych, wskazujących na poprawność przyjętych założeń modelowych.
EN
High-alloy corrosion-resistant ferritic-austenitic steels and cast steels are a group of high potential construction materials. This is evidenced by the development of new alloys both low alloys grades such as the ASTM 2101 series or high alloy like super or hyper duplex series 2507 or 2707 [1-5]. The potential of these materials is also presented by the increasing frequency of sintered components made both from duplex steel powders as well as mixtures of austenitic and ferritic steels [6, 7]. This article is a continuation of the problems presented in earlier works [5, 8, 9] and its inspiration were technological observed problems related to the production of duplex cast steel. The analyzed AISI A3 type cast steel is widely used in both wet exhaust gas desulphurisation systems in coal fired power plants as well as in aggressive working environments. Technological problems such as hot cracking presented in works [5, 8], with are effects of the rich chemical composition and phenomena occurring during crystallization, must be known to the technologists. The presented in this work phenomena which occur during the crystallization and cooling of ferritic-austenitic cast steel were investigated using numerical methods with use of the ThermoCalc and FactSage® software, as well with use of experimental thermal-derivative analysis.
EN
The paper presents results of measuring heat diffusivity and thermal conductivity coefficients of used green foundry sand in temperature range ambient – 600°C. During the experiments a technical purity Cu plate was cast into the green-sand moulds. Basing on measurements relationships of the measured properties were evaluated. It was confirmed that the obtained relationships are complex and that water vaporization strongly influences thermal conductivity of the moulding sand in the first period of the mould heating by the poured and solidified casting.
EN
In order to predict the distribution of shrinkage porosity in steel ingot efficiently and accurately, a criterion R√L and a method to obtain its threshold value were proposed. The criterion R√L was derived based on the solidification characteristics of steel ingot and pressure gradient in the mushy zone, in which the physical properties, the thermal parameters, the structure of the mushy zone and the secondary dendrite arm spacing were all taken into consideration. The threshold value of the criterion R√L was obtained with combination of numerical simulation of ingot solidification and total solidification shrinkage rate. Prediction of the shrinkage porosity in a 5.5 ton ingot of 2Cr13 steel with criterion R√L>0.21 m・℃1/2・s-3/2 agreed well with the results of experimental sectioning. Based on this criterion, optimization of the ingot was carried out by decreasing the height-to-diameter ratio and increasing the taper, which successfully eliminated the centreline porosity and further proved the applicability of this criterion.
EN
The suspension of copper droplets in the slag is considered. The copper/slug suspension is delivered as the product from the direct-to-blister process which is applied in the KGHM – Polska Miedź (Polish Copper) S.A. factory. The droplets / slag suspension was treated by a special set of reagents (patented by the authors) to improve the coagulation process. On the other hand, the observations are made to estimate if the melting / reduction process in the furnace is sufficiently effective to avoid a remaining of carbon in the copper droplets. The coagulation process was carried out in the crucible (laboratory scale). However, conditions imposed to the coagulation / solidification process in the laboratory scale were to some extent similar to those applied usually in the industry when the suspension is subjected to the analogous treatment in the electric arc-furnace. Some suggestions are formulated how to improve the industrial direct-to-blister process.
EN
Thermal processes in domain of thin metal film subjected to a strong laser pulse are discussed. The heating of domain considered causes the melting and next (after the end of beam impact) the resolidification of metal superficial layer. The laser action (a time dependent bell-type function) is taken into account by the introduction of internal heat source in the energy equation describing the heat transfer in domain of metal film. Taking into account the extremely short duration, extreme temperature gradients and very small geometrical dimensions of the domain considered, the mathematical model of the process is based on the dual phase lag equation supplemented by the suitable boundary-initial conditions. To model the phase transitions the artificial mushy zone is introduced. At the stage of numerical modeling the Control Volume Method is used. The examples of computations are also presented.
EN
A new Computer-Aided Design approach is introduced for design of steel castings taking into account the feeding ability in sand moulds. This approach uses the geometrical modeling by a CAD-program, in which the modul “Castdesigner” is implemented, which includes the feeding models of steel castings. Furthermore, the feeding ability is guaranteed immediately during the design by an interactive geometry change of the casting cross section, so that a directional feeding of the solidifying casting from the installed risers is assured.
EN
The paper analyses specific defects of castings produced by semi-solid casting process, especially rheocasting method SEED, which uses mechanical swirling for reaching proper structure in semisolid state with high content of solid fraction. Heat treated alloy AlSi7Mg0.3 was applied for producing an Engine Bracket casting part. For observing structure, metallographic observation by light and SEM microscopy was used. To analyse the process, software ProCAST was used to simulate the movements in shot chamber and filling of the mold.
PL
W pracy przedstawiono wyniki badań nad zjawiskiem skurczu liniowego krzepnącego i stygnącego odlewu siluminowego. W prowadzonych badaniach zastosowano formy metalowe odwzorowujące odlew pionowego pręta testowego o przekroju okrągłym (stałym lub zmiennym). Zastosowanie dwóch wariantów form zagwarantowało uzyskanie porównywalnych warunków stygnięcia przy uzyskaniu warunków skurczu ideowo swobodnego (forma o zbieżności 1:100, niedzielona) oraz skurczu hamowanego (forma walcowa, dzielona) jedynie na powierzchni odlew-forma. Na podstawie rejestrowanych zmian temperatury odlewu oraz zmian wymiaru osiowego krzepnącego odlewu i formy testowej określono kinetykę skurczu liniowego oraz zmian współczynnika liniowej rozszerzalności cieplnej w funkcji temperatury Przedstawiono wyniki badania skurczu liniowego uzyskane w formie ze zbieżnością oraz bez niej (walcowej).
EN
The paper presents results of research on the phenomenon of linear shrinkage and cooling silumin. In this study using a metal mold test mapping casting circular cross-section vertical rod (fixed or variable). Use of two variant forms of guarantees comparable cooling conditions in obtaining spasm of ideological freedom (form convergence of 1:100, unshared) and inhibits the contractions (as a cylindrical joint) only the surface of the mold. Based on the recorded temperature changes and changes in the casting of the axial dimension of the casting mold and solidification of the test set, certain intensity and the change of the linear shrinkage coefficient of linear expansion of heat as a function of temperature. Shows the result of research in the form of linear contraction and convergence without it (cylindrical).
PL
W artykule opisano szereg metod odlewania w stanie ciekło-stałym SSM prowadzących do otrzymania odlewów o strukturze bezdendrytycznej, która wpływa znacznie na poprawę właściwości mechanicznych odlewu. Do wytworzenia zawiesiny metalowej zastosowano metodę RSF (Rapid Slurry Forming). Bazując na matematycznym opisie procesu wytwarzania zawiesiny metalowej w procesie RSF, wykonano odlewy ze stopu AlSi7Mg z zawiesiny zawierającej 30% objętościowo fazy stałej uzyskanej w wyniku mieszania i roztapiania ochładzalnika. Przedstawiono strukturę uzyskanych odlewów grawitacyjnych. Wykonano pomiar temperatury w czasie wytwarzania zawiesiny i krzepnięcia odlewu i porównano z wartościami obliczonymi.
EN
The article describes several variations of the semi-solid metal processing (SSM) technique rendering castings with non-dendritic structure and significantly improved mechanical properties. The metal slurry was produced using the Rapid Slurry Forming (RSF) method. Based on a mathematical description of the RSF process of the metal slurry fabrication, castings were poured from the AlSi7Mg alloy in the form of a slurry with 30 vol. % solid fraction obtained by stirring and melting down of a chill element. Shown is the structure obtained by gravity casting. The temperature was measured during the slurry preparation and solidification of casting. The data obtained experimentally were compared with the theoretically calculated values.
PL
W pracy zaprezentowano wyniki symulacji numerycznej krzepnięcia. Prezentowany model obliczeniowy zbudowany jest na podstawie równania przewodzenia ciepła z członem źródłowym w jawnym sformułowaniu pojemnościowym. Model narastania fazy stałej jest zgodny z pośrednim modelem, w którym zakładana jest skończona dyfuzja domieszki w fazie ciekłej oraz brak dyfuzji domieszki w fazie stałej. Wynikające z modelu równania różniczkowe rozwiązane są za pomocą metody elementów skończonych. Obliczenia były realizowane na komputerach o pamięci rozproszonej. Wykonano testy dla siatek elementów skończonych składających się z maksymalnie 25 milionów elementów. Testy skalowalności były przeprowadzone dla maksymalnie 2048 procesorów.
EN
The results of numerical simulations are presented in this paper. Computational model presented in this work uses heat transfer equation with heat source term in explicit enthalpy formulation. An indirect model for a solid phase growth was used. The indirect model assumes finite diffusion of inclusion in liquid phase and no diffusion in solid state. Resulting differential equations are solved with use of Bubnov-Galerkin Finite Element Method (space discretization). The calculations were performed on computer cluster with distributed memory positioned 7th on TOP500 list from November 2014. We carried out tests using meshes of up to 25 million of tetrahedral elements. The scalability tests were conducted for up to 2048 processor cores.
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