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1

Investigation of The Effect of Mechanical Vibration Applied During Solidification on The Microstructure and Properties of Aluminum 356 Alloy

Özgü Taha Süreyya, Çalın Recept, Tanış Naci Arda

Archives of Foundry Engineering

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2024

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Vol. 24, iss. 1

26--31

EN

Manufacturing by casting method in aluminum and its alloys is preferred by different industries today. It may be necessary to improve the mechanical properties of the materials according to different industries and different strength requirements. The mechanical properties of metal alloys are directly related to the microstructure grain sizes. Therefore, many grain reduction methods are used during production or heat treatment. In this study, A356 alloys were molded into molds at 750°C and exposed to vibration frequency at 0,8.33, 16.66, 25, and 33.33 Hz during solidification. Optical microscopes images were analyzed in image analysis programs to measure the grain sizes of the samples that solidified after solidification. In addition, microhardness tests of samples were carried out to examine the effect of vibration and grain reduction on mechanical behavior. In the analyzes made, it was determined that the grain sizes decreased from 54.984 to 26.958 μm and the hardness values increased from 60.48 to 126.94 HV with increasing vibration frequency.

2

Research on closed-loop utilization of engineering waste mud in engineering sites

Zhan Jinsheng, Zhao Shichun

Materials Science Poland

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2023

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Vol. 41, No. 3

99--110

EN

The large amount of waste mud generated during construction projects makes it difficult to implement closed-loop on-site treatment, resulting in the inability to achieve zero emissions, which not only wastes land resources but also pollutes the environment. This article first studied the flocculation effect and mechanism of two flocculants. Then, the treated sediment was used to prepare fluidized solidified soil, and the effect of flocculants in the sediment on the performance of fluidized solidified soil was studied. Finally, this technology of flocculation and re-solidification was applied in engineering. The results showed that the composite effect of adding PAC flocculant first and then APAM flocculant in the mud had the best mud-water separation effect. The soil was combined with the flocculants to prepare fluidized solidified soil that can effectively improve the strength and water stability of the solidified soil. Through engineering applications, it has been proven that closed-loop utilization of engineering waste mud can be achieved on-site. Therefore, this work provides a new method for achieving zero emissions through closed-loop utilization of engineering waste mud on-site and innovative experience for the construction of "waste-free cities".

3

Morphology and Distribution of α-Al and Mn-rich Phases in Al-Si-Mn Alloys under an Electromagnetic Stirring

Mikołajczak P.

Archives of Foundry Engineering

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2023

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Vol. 23, iss. 3

74--87

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.

4

Flow Effect on Si Crystals and Mn-Phases in Hypereutectic and Eutectic Al-Si-Mn Alloys

Mikołajczak Piotr

Archives of Foundry Engineering

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2023

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Vol. 23, iss. 4

72--86

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.

5

Evaluation of the Effect of External Conditions During Crystallization and Solidification on the Final Structure of AlSi7Mg

Radkovský Filip, Gawronová Martina, Kroupová Ivana

Archives of Foundry Engineering

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2023

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Vol. 23, iss. 1

118--123

EN

Abstract The paper deals with the possibilities of influencing the final microstructure of aluminium alloy castings by changing the external conditions of crystallization and solidification. Aluminum alloys, especially Al-Si alloys, are nowadays one of the most used non-ferrous metal alloys, especially due to their mass application in the automotive field. It is in this industry that extreme emphasis is placed on the quality of cast parts with regard to safety. For this reason, a key production parameter is the mastery of the control of the resulting microstructure of the castings and the associated internal quality, which is subject to high demands defined by international standards. The aim of the experiment of this paper is to evaluate the effect of different preheating of the metal mould on the resulting structure and hardness of test castings made of AlSi7Mg0.3 material. The hardness measurement will be evaluated on a hardness tester. The parameter SDAS, Microporosity, Content of excluded eutectic will be evaluated. Dependencies will be found and plotted.

6

Numerical Evaluation of the Impact of Riser Geometry on The Shrinkage Defects Formation in the Solidifying Castin

Sowa L., Skrzypczak T., Kwiatoń P.

Archives of Metallurgy and Materials

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2022

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Vol. 67, iss. 1

181--187

EN

The work concerns of modeling the process of manufacturing machine parts by casting method. Making a casting without internal defects is a difficult task and usually requires numerous computer simulations and their experimental verification at the prototyping stage. Numerical simulations are then of priority importance in determining the appropriate parameters of the casting process and in selecting the shape of the riser for the casting fed with it. These actions are aimed at leading shrinkage defects to the riser, so that the casting remains free from this type of defects. Since shrinkage defects usually disqualify the casting from its further use, this type of research is still valid and requires further work. The paper presents the mathematical model and the results of numerical simulations of the casting solidification process obtained by using the Finite Element Method (FEM). A partial differential equation describing the course of thermal phenomena in the process of 3D casting creating was applied. This equation was supplemented with appropriate boundary and initial conditions that define the physical problem under consideration. In numerical simulations, by selecting the appropriate shape riser, an attempt was made to obtain a casting without internal defects, using a simple method of identifying their location. This is the main aim of the research as such defects in the casting disqualify it from use.

7

Solidification/Stabilization Treatment for organic oil immobilization in Algerian Petroleum Drill Cuttings: Optimization and Acceptance Tests for Landfilling

Abbas Abbas Hadj, Aissa Abidi Saad, Mohamed Khodja, Farad Sagala, Messaoud Hacini

Archives of Environmental Protection

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2022

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Vol. 48, no. 2

95--105

EN

Hassi Messaoud oil field is one of the most important fields in Algeria and the world, because it covers an important quantity of total Crude Oil Production in Algeria. Furthermore, two-thirds of this oil field is underexplored or not explored. Therefore, the drilling process of petroleum wells in this field is a continuous process that results in significant drilling waste. This implies that enormous noxious quantities of drilling waste are produced daily that require treatment via solidification/stabilization (S/S) process before being landfilled. These types of wastes have pollution concentration that significantly exceeds the safety standards. In this study, we focus on the factors affecting the solidification/stabilization treatment of the drill cuttings obtained from Hassi Messaoud oil field and the process optimization. The solidification/stabilization is performed using the cement as binder, and sand, silicate, organophilic clay and activated carbon as additives. The study has been divided into two steps: (i) Determining the optimum ratio of each element used in the S/S process for the organic element (hydrocarbon) elimination, (ii) Combining the optimum ratios found in the previous step to determine the optimal mixture. The obtained results in the first step showed that the optimum ratio for the cement-to-drill cuttings mass ratio is 0.09:1. For the additives-to-drill cuttings mass ratios are 0.04:1, 0.006:1, 0.013:1 and 0.013:1 for the sand, sodium silicate, organophilic clay and activated carbon, respectively. An optimum formula is found whose main finding shows that the hydrocarbon content of our sample is dropped from 9.40 to 1.999%. Many tests’ results such as matrix permeability, resistance to free compression and heavy metals rate before and after S/S process were investigated before landfilling. Besides that, in the light of outcomes achieved by this assessment, these harmful cuttings can be converted into a useful product that helps in reducing the environmental foot prints.

8

Effect of filler metal composition on microstructural and mechanical characterization of dissimilar welded joint of nitronic steel and super duplex stainless steel

Maurya Anup Kumar, Pandey Chandan, Chhibber Rahul

Archives of Civil and Mechanical Engineering

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2022

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Vol. 22, no. 2

art. no. e90, 1--28

EN

The present paper experimentally investigates the effect of filler metal on the mechanical behavior, solidification, and microstructure of the super duplex stainless steel (sDSS2507) and nitronic steel (N50) dissimilar welded joint. This dissimilar joint is primarily applicable in the subsea control unit for high-pressure tubing and coupler assembly. For this investigation, the gas tungsten arc welding process (GTAW) employed the super duplex filler ER2594 and carbon steel grade ER70S-2 filler. The weld's structural integrity has been assessed to compare both the fillers through multiple investigations on the joint. The microstructure characterization of the base metal and as-welded specimen was carried out using an optical microscope (OM) and scanning electron microscope (SEM). Super duplex filler ER2594 weld solidified in primary ferritic mode with precipitation of several reformed austenite in the ferrite matrix, whereas ER70S-2 filler weld had long marten site laths embedded in ferrite matrix. The microstructural study reported the presence of microsegregation and Type II boundary formation. The type-II boundary is detected close to the fusion boundary at the N50 and the sDSS 2507 side of the ER70S-2 weldment. The Vickers microhardness test, Charpy impact test, and the tensile test were performed to obtain the mechanical properties of this joint. The microhardness investigation of the weld zone of ER2594 and ER70S-2 shows the average hardness of 287.34±10 Hv0.5 and 372.36±10 Hv0.5, respectively. The peak hardness of 410 Hv0.5 was observed in the weld zone of ER70S-2. The formation of large marten site laths in the ferrite matrix in the weld zone leads to higher hardness in ER70S-2 filler compared to the precipitation of softer reformed austenite in the ER2594 fller. The average impact toughness result of ER2594 and ER70S-2 is 165±5 J and 110±8 J, respectively. The Charpy impact trials showed the ductile fracture mode by employing ER2594 filler, while ER70S-2 showed the mixed fracture mode (ductile-brittle). The weldment tensile strength of filler ER2594 and ER70S-2 is 897 MPa and 873 MPa, respectively. The tensile test results indicate the ductile fracture mode for both fillers, and the failures were detected in sDSS2507.

9

Hybrid nano improved phase change material for latent thermal energy storage system: Numerical study

Benlekkam Mohamed Lamine, Nehari Driss

Archive of Mechanical Engineering

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2022

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LXIX, nr 1

77--98

EN

The phase change materials (PCM) are widely used in several applications, especiallyi n the latent heat thermal energy storage system (LHTESS). Due to the very low thermal conductivity of PCMs. A small mass fraction of hybrid nanoparticles TiO 2–CuO (50%–50%) is dispersed in PCM with five mass concentrations of 0%, 0.25%, 0.5%, 0.75% and 1 mass % to improve its thermal conductivity. This article is focused on thermal performance of the hybrid nano-PCM (HNPCM) used for the LHTESS. A numerical model based on the enthalpy-porosity technique is developed to solve the Navier-Stocks and energy equations. The computations were conducted for the melting and solidification processes of the HNPCM in a shell and tube latent heat storage (LHS). The developed numerical model was validated successfully with experimental data from the literature. The results showed that the dispersed hybrid nanoparticles improved the effective thermal conductivity and density of the HNPCM. Accordingly, when the mass fraction of a HNPCM increases by 0.25%, 0.5%, 0.75% and 1 mass %, the average charging time improves by 12.04 %, 19.9 %, 23.55%, and 27.33 %, respectively. Besides, the stored energy is reduced by 0.83%, 1.67%, 2.83% and 3.88%, respectively. Moreover, the discharging time was shortened by 18.47%, 26.91%, 27.71%, and 30.52%, respectively.

10

Investigation of the influence of liquid phase motion on the solidification process in the three-dimensional region

Węgrzyn-Skrzypczak Ewa

Journal of Applied Mathematics and Computational Mechanics

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2021

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Vol. 20, nr 1

103--111

EN

In this paper, the numerical model of solidification process with the motion of the liquid phase is presented. The mathematical description of the considered problem is based on the heat conduction equation with convective term and the Navier-Stokes equations with continuity equation. The numerical model uses the Finite Element Method (FEM). The simulations of the solidification process with or without the fluid motion effect are presented and discussed.

11

Influence of Liquid Metal Movements on the Casting Creation

Sowa Leszek, Skrzypczak Tomasz, Kwiatoń Paweł

Archives of Metallurgy and Materials

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2021

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Vol. 66, iss. 2

489--495

EN

Knowledge about complex physical phenomena used in the casting process simulation requires continuous complementary research and improvement in mathematical modeling. The basic mathematical model taking into account only thermal phenomena often becomes insufficient to analyze the process of metal solidification, therefore more complex models are formulated, which include coupled heat-flow phenomena, mechanical or shrinkage phenomena. However, such models significantly complicate and lengthen numerical simulations; therefore the work is limited only to the analysis of coupled thermal and flow phenomena. The mathematical description consists then of a system of Navier-Stokes differential equations, flow continuity and energy. The finite element method was used to numerically modeling this problem. In computer simulations, the impact of liquid metal movements on the alloy solidification process in the casting-riser system was assessed, which was the purpose of this work, and the locations of possible shrinkage defects were pointed out, trying to ensure the right supply conditions for the casting to be free from these defects.

12

Role of Metal Quality and Porosity Formation in Low Pressure Die Casting of A356: Experimental Observations

Gursoy O., Nordmak A., Syversten F., Colak M., Tur K., Dispinar D.

Archives of Foundry Engineering

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2021

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Vol. 21, iss. 1

5--10

EN

Porosity is one of the major problems in casting operations and there are several discussions in the literature about the porosity formation in aluminum castings. Bifilms are the defects that are introduced into the melt by turbulence. They can be detected with reduced pressure test and presented numerically by measuring bifilm index. The measure of bifilm index is the sum of total oxide length given in millimeters from the cross-section of reduced pressure test sample solidified under 0.01 MPa. In this work, low pressure die casting (LPDC) unit was built in an attempt to enhance the producibility rate. The unit consists of a pump housing that was placed inside the melt in the melting furnace where the pressure was applied instead of the whole melt surface. It was observed that the melt quality of A356 alloy was deteriorated over time which had led to higher porosity. This was attributed to the increased oxide thickness of the bifilm by the consumption of air in between the folded oxides. A relationship was found between bifilm index and pore formation.

13

Effect of cooling rate on microstructure and microhardness of hypereutectic Al–Ni alloy

Carrara A. P., Kakitani R., Garcia A., Cheung N.

Archives of Civil and Mechanical Engineering

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2021

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Vol. 21, no. 1

230--238

EN

High solidification cooling rates during unsteady-state conditions of solidification of Al-based alloys can induce different microstructural length scales or metastable phases, leading to improved properties. The present study aims to characterize the microstructural arrangement of the hypereutectic Al–8 wt%Ni alloy, unidirectionally solidified in unsteady-state heat flow conditions, examining the influence of the cooling rate in the development of the Al–Al3Ni eutectic and the primary phase. A columnar-to-equiaxed macrostructural transition is shown to occur at a solidification cooling rate [...] of about 4.8 °C/s, with different microstructures associated with each morphological zone. The observation of microstructures of hypoeutectic, eutectic and hypereutectic Al–Ni alloys, has permitted an asymmetric coupled zone diagram to be proposed. The microstructural interphase spacings of the Al–8 wt%Ni alloy are experimentally determined and correlated to [...], and the Vickers microhardness (HV) is shown to decrease with the increase in such spacings. The higher experimental HV profile of the examined hypereutectic alloy as compared to that of the eutectic Al–Ni alloy is attributed to the formation of a supersaturated solid solution of Ni in α-Al.

14

Analysis and Validation of Database in Computer Aided Design of Jewellery Casting

Ignaszak Z., Wojciechowski J.

Archives of Foundry Engineering

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2020

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Vol. 20, iss. 1

9--16

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.

15

A Sequential FEM-SPH Model of the Heating-Remelting-Cooling of Steel Samples in the Gleeble 3800 Thermo-Mechanical Simulator System

Hojny M.

Archives of Foundry Engineering

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2020

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Vol. 20, iss. 3

60--68

EN

This article presents a sequential model of the heating-remelting-cooling of steel samples based on the finite element method (FEM) and the smoothed particle hydrodynamics (SPH). The numerical implementation of the developed solution was completed as part of the original DEFFEM 3D package, being developed for over ten years, and is a dedicated tool to aid physical simulations performed with modern Gleeble thermo-mechanical simulators. Using the developed DEFFEM 3D software to aid physical simulations allows the number of costly tests to be minimized, and additional process information to be obtained, e.g. achieved local cooling rates at any point in the sample tested volume, or characteristics of temperature changes. The study was complemented by examples of simulation and experimental test results, indicating that the adopted model assumptions were correct. The developed solution is the basis for the development of DEFFEM 3D software aimed at developing a comprehensive numerical model allows the simulation of deformation of steel in semi solid state.

16

The Study of the Tensile Strength of AlSi21CuNiMg Silumin in the Final Stage of Solidification and the Initial Stage of Cooling

Romankiewicz Remigiusz

Journal of Casting & Materials Engineering

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2019

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Vol. 3, no. 3

57--61

EN

The paper presents the results of tensile strength tests of AlSi21CuNiMg silumin made on a test stand. Silumin was under examination in an unmodified state and after modification with AlCu19P1.4 master alloy in quantity of 0.2% in relation to the mass of the alloy. Using a scanning microscope, the surface fractures obtained from tensile tests were tested. The structure and profiles of fractures were examined using an optical microscope. Modification of the tested silumin resulted in a favorable fragmentation and regular distribution of the crystals of the primary silicon in the alloy structure, which led to an almost twofold increase in the strength of the silumin samples at the final solidification stage from 3.5 to 6.6 MPa. As a result of these changes, the resistance of silumin to hot cracks should increase, which is of great importance when casting hypereutectic silumin in a metal mould that strongly inhibits the shrinkage of the castings.

17

Utilization of Blast Furnace Slag for Immobilization of Copper Ions from Solution

Mucha Martin, Blahova Lenka, Navratilova Zuzana, Pesova Karolina, Jurica Tomas, Kolnicenko Dimitrij

Inżynieria Mineralna

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2019

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R. 21, nr 1

25--30

EN

Disposal of wastes containing metal ions such as Cu(II) ions is serious problem nowadays. Various materials are utilized for the purpose of immobilization of Cu(II) ions. Attractive type of material is represented by slags – waste from the metallurgical industry. Raw and alkali-activated blast furnace slag were studied for the purpose of immobilization of Cu(II) ions from the aqueous solution and for disposal of Cu(II) containing wastes. Slags were saturated by Cu(II) ions. Amount of Cu(II) deposited on the raw slag was 6.35 ± 0.12 mg/g and amount deposited on the alkali-activated slag was 151.37 ± 0.95 mg/g. The saturated materials were thermally treated at 100, 500, and 1000°C. The thermal treatment leads to the slight structural changes in the case of raw slag and to the significant structural changes in the case of alkali-activated slag. Cu(II) ions probably incorporate to the matrix of materials. The materials based on alkali-activated slag exhibit higher stability to the leaching of Cu(II) ions compared to raw slag based materials when only 0.13% of the total immobilized amount of Cu(II) ions was released to the solutions during the leaching experiment in the case of alkali activated slag compared to 12% in the case of raw slag. The higher temperature of treatment leads to more stable material in the case of both initial slags. The studied materials are less stable under the acidic conditions in comparison with the neutral and alkaline conditions. Alkali-activated blast furnace slag could be promising material for the Cu(II) ions immobilization and for the safe disposal of Cu(II) containing wastes.

PL

Utylizacja odpadów zawierających jony metali, takich jak jony Cu (II), stanowi obecnie poważny problem. W celu immobilizacji jonów Cu (II) stosuje się różne materiały. Atrakcyjny rodzaj materiału reprezentują żużle – odpady z przemysłu metalurgicznego. Surowe i aktywowane alkalicznie żużle wielkopiecowe badano pod katem immobilizacji jonów Cu (II) z roztworu wodnego i możliwości składowania odpadów zawierających Cu (II). Żużle były nasycone jonami Cu (II). Ilość Cu (II) osadzonego na surowym żużlu wynosiła 6,35 ± 0,12 mg/g, a ilość osadzona na żużlu aktywowanym alkaliami wynosiła 151,37 ± 0,95 mg/g. Nasycone materiały poddano obróbce termicznej w 100, 500 i 1000°C. Obróbka termiczna prowadzi do niewielkich zmian strukturalnych w przypadku surowego żużla i znacznych zmian strukturalnych w przypadku żużla aktywowanego alkaliami. Jony Cu (II) prawdopodobnie wypełniają matrycę materiałów. Materiały na bazie żużla aktywowanego alkaliami wykazują wyższą stabilność wymywania jonów Cu (II) w porównaniu z żużlami surowymi. Uzyskano immobilizację wynoszącą 0,13% całkowitej unieruchomionej ilości jonów Cu (II)dla żużla aktywowanego i 12% w przypadku żużla surowego. Obróbka w wyższej temperaturze prowadzi do uzyskania bardziej stabilnego materiału w przypadku obu rodzajów żużla. Badane materiały są mniej stabilne w warunkach kwasowych niż w warunkach obojętnych i alkalicznych. Żużel wielkopiecowy aktywowany alkaliami może być obiecującym materiałem do immobilizacji Cu (II) i do bezpiecznego usuwania odpadów zawierających Cu (II).

18

Projektowanie i rozwój modułu obliczeniowego hydrodynamiki cząstek rozmytych pakietu DEFFEM 3D

Hojny Marcin, Dębiński Tomasz

Hutnik, Wiadomości Hutnicze

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2019

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Vol. 86, nr 4

101--107

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.

19

Solidification as a process of treatment of post-coagulation sludge from the water treatment plant

Płonka Izabela, Pieczykolan Barbara, Kuszaj Dawid, Rzeźniczek Grzegorz

Ecological Chemistry and Engineering. A

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2019

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Vol. 26, nr 1-2

85--97

EN

Post-coagulation sludge is a mixture of pollutants removed from water and coagulants, which was added to the water. It has a hydrophilic and colloidal character. It is important to search processes whereby this sludge could be reused or eventually disposed of. The studies of solidification of post-coagulation sludge were carried out. The solidification process consists in the appropriate and rapid mixing the sludge with the material used for solidification in order to ensure the adequate homogenization conditions. The reagent used in solidification absorbs water contained in the sludge as a result of rapid homogenization with the sludge due to hydration, in a strongly exothermic process. The excess water evaporates form the sludge. This reduces the mass and volume of the sludge and leads to the formation of granules. During the tests, quicklime and cement Gorkal 40, Gorkal 50 and Gorkal 70 were used as a solidifying material, in doses of 0.7; 1.4; 2.1; 2.8; 3.5 g/kg TS. During the maturing process of the lime-sludge and cement-sludge mixtures, changes in the total solids concentrations were checked. The obtained test results show that increasing the solidification material dose and extending the maturation time results in a significant increase in the total solids concentration of the mixtures. Changing the structure and consistency of the sludge from plastic to solid gives the possibility to use sludge as a building material, for the reclamation of dumps, hardening roadsides or creating slopes and embankments.

PL

W Stacjach Uzdatniania Wody (SUW) powierzchniowej powstają osady pokoagulacyjne. Stanowią one mieszaninę usuniętych z wody zanieczyszczeń oraz dodanych do niej koagulantów wykazując hydrofilowo-koloidalny charakter. Ponadto charakteryzują się wysokim uwodnieniem powyżej 99%. SUW zobligowane są do wprowadzania rozwiązań umożliwiających optymalne gospodarowanie osadami. W związku z tym istotne jest poszukiwanie procesów, w wyniku których osady te mogłyby być ponownie wykorzystane lub ostatecznie unieszkodliwione. Przeprowadzono badania zestalania osadów pokoagulacyjnych. Proces zestalania polega na odpowiednim oraz szybkim mieszaniu osadu z użytym materiałem zestalającym, aby zapewnić odpowiednie warunki homogenizacji. Zastosowany reagent w wyniku szybkiej homogenizacji z osadem na skutek hydratacji, w procesie silnie egzotermicznym, pochłania wodę zawartą w osadach, której nadmiar odparowuje. Powoduje to zmniejszenie masy i objętości osadów i prowadzi do powstania granulatu. Podczas badań jako materiału zestalającego użyto wapna palonego oraz cementów Górkal 40, Górkal 50 i Górkal 70 w dawkach 0,7; 1,4; 2,1; 2,8; 3,5 g/kg sm. W trakcie procesu dojrzewania mieszaniny wapienno-osadowej oraz cementowo-osadowej sprawdzano zmiany stężenia suchej masy. Uzyskane wyniki badań wykazały, że zwiększenie dawki materiału zestalającego oraz wydłużenie czasu dojrzewania powoduje znaczny wzrost stężenia suchej masy mieszanin. Zmiana struktury i konsystencji osadów od plastycznej do stałej daje możliwość wykorzystania osadów jako materiału budowlanego, do rekultywacji wysypisk, utwardzania poboczy dróg czy tworzenia skarp i wałów.

20

The deviation from eutectic composition in boundary layer for eutectic growth: a phase-field study

Tu Zhixin, Zhou Jianxin, Yin Yajun, Ji Xiaoyuan, Shen Xu

Archives of Metallurgy and Materials

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2019

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Vol. 64, iss. 1

119--123

EN

In this paper, the deviation from eutectic composition in boundary layer for eutectic growth is studied by phase-field method. According to a series of artificial phase diagram, the lamellar eutectic growth of these alloy is simulated during directional solidification. At steady state, average growth velocity of eutectic lamella is equal to the pulling velocity. With the increasing of the liquidus slope of β phase, the average composition in boundary layer would deviate from eutectic composition and the deviation increases. The constitutional undercooling difference between both solid phases caused by the deviation increases with the increasing of the deviation. The β phase would develop a depression under the influence of the deviation.