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1

Influence of Cast Iron Modification on Free Vibration Frequency of Casting

Konopka Z., Łągiewka M., Zyska A.

Archives of Foundry Engineering

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2020

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Vol. 20, iss. 1

23--26

EN

The paper presents the results of investigations concerning the influence of gray cast iron modification on free vibration frequency of the disc casting. Three different chemical composition melts of gray cast iron were prepared in induction furnace. During gravity casting 0.05% and 0.3% mass of the Inolate modifier was added on stream of metal for changing graphite flakes in castings. Sound signal vibration of cast iron sample was registered by means on microphone for free vibration frequency measurements. Decreasing of free vibration frequency of modified cast iron in comparison with non modified castings was observed. Higher contents of modifier causes more decreasing of free vibration frequency. Cast iron with smaller contents of carbon and silicon have higher free vibration frequency in comparison with eutectic composition cast iron. Hardness of examined cast iron is lower when the more modifier is added during modification process. Free frequency is smaller with smaller Brinell hardness of disc casting. It was concluded that control of free vibration frequency of disc castings by means of chemical composition and modification process can improved comfort and safety of working parts.

2

Impact strength of squeeze casting AlSi13Cu2–CF composite

Zyska A., Konopka Z., Łągiewka M.

Archives of Foundry Engineering

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2020

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Vol. 20, iss. 2

49--52

EN

The paper presents the results of research on microstructure and impact strength of AlSi13Cu2 matrix composite reinforced by Ni-coating carbon fibers (CF) with a volume fraction of 5%, 10% and 15%. The composite suspensions were prepared using by stirring method and subsequently squeeze casted under different pressures of 25, 50, 75 and 100 MPa. As part of the study, fiber distribution in aluminum matrix was evaluated and variation in impact strength of composite as a function of the carbon fibers volume fraction and pressure applied were determined. It has been found that the presence of Ni coating on carbon fibers clearly improves their wettability by liquid aluminum alloy and in combination with the stirring parameters applied, composite material with relatively homogeneous structure can be produced. Charpy's test showed that the impact strength of composite reaches the highest value by carrying out the squeeze casting process at 75 MPa. In the next stage of research, it was found that the impact strength of composites increases with the increase of carbon fibers volume fraction and for 15% of fibers is close to 8 J/cm2. Observations of fracture surfaces have revealed that crack growth in the composites propagates with a quasi-cleavage mechanism. During the creation of the fracture, all fibers arranged perpendicular to its surface were sheared. At the same time, the metal matrix around the fibers deformed plastically creating characteristic ductile breaks. The fracture surface formation through the fibers indicates a cohesive and strong connection of the reinforcement with the matrix. In addition to the phenomena mentioned, debonding the fiber-matrix interfaces and the formation of voids between components were observed on the fracture surface.

3

Badanie wpływu podciśnienia w formie na chropowatość powierzchni odlewów

Łągiewka M., Konopka Z., Zyska A.

Prace Instytutu Odlewnictwa

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2018

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Vol. 58, no. 1

3--11

PL

W artykule przedstawiono wyniki badań wpływu podciśnienia w formie i układzie zalewania na chropowatość powierzchni odlewów. Badania chropowatości powierzchni wykonano na odlewach ze stopu EN AB 46000 wykonanych metodą odlewania ciśnieniowego na maszynie Vertacast z zastosowaniem zmiennego podciśnienia w formie. Stwierdzono zmniejszenie chropowatości powierzchni odlewów ze zmniejszeniem ciśnienia w formie na podstawie wartości różnych charakterystycznych parametrów chropowatości. Badania chropowatości odlewów wykonano na urządzeniu Hommel Tester T1000.

EN

The article discusses the results of the studies of the effect of negative pressure in the mould and the casting system on the roughness of the casts' surfaces. Roughness tests were performed on casts made of alloy EN AB 46000, by means of the pressure casting method in the Vertacast machine, and with the use of varying negative pressure in the mould. The surface roughness of the casts decreasing with a decrease in the pressure in the mould was determined based on the values of different characteristic surface roughness parameters. The cast roughness examinations were conducted on the Hommel Tester T1000 device.

4

Influence of the Home Scrap Content on the Service Life of Equipment Used in High Pressure Die Casting of AZ91 Alloy

Konopka Z., Łągiewka M., Zyska A.

Archives of Foundry Engineering

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2018

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Vol. 18, iss. 2

173--176

EN

The results of estimation of home scrap addition in charge influence on durability and wear of casting instrumentation life in the high-pressure casting technology using the hot chamber machine of alloy of AZ91 are presented. The wear of the following elements of the casting instrumentation so-called "casting set" as: syphon, plunger, sliding-rings, nozzle and injection moulding nozzle was estimated. A wear was estimated quantitative by registering the number of mould injections for different charges to the moment of element damage supervision. A damage had to be at such level that liquidated an element from further exploitation and necessary was an exchange on new or regeneration. In a final result allowed it the detailed determination of durability of the applied rigging elements in dependence on the type of the applied type of melt. It is noticed, that together with the increase of home-scrap participation in the charge wear of pressure machine instrumentation elements increases.

5

Castability and Structure of Dental Alloys on a Nickel Base

Zyska A., Konopka Z., Łągiewka M., Kordas P.

Archives of Foundry Engineering

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2018

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Vol. 18, iss. 1

139--144

EN

The results of castability and structures researches of two nickel base alloys - Ceranium CN and Magnum AN applied on casting of the crowns and dental bridges are presented. Studies were carried out on the alloys cast under the centrifugal force to the moulds made by the lost wax method using production line of ROKO. Having regard to a specific technology of casting and possibility of ROKO production line, to the estimation of alloys castability a spiral test was adjusted with a 0,8 mm and a 2,5 mm diameter of test casting. Measuriements executed on a 20 test castings allowed to establish, that castability of Magnum AN alloy was 65 % greater than castability of Ceranium NC alloy. The results of thermodynamics calculations of the equilibrium and nonequilibrium crystallization (Scheil model) of the investigated alloys are presented too. The characteristic temperatures of phase transformation and forecast phase composition of alloys for both kind of crystallization were calculated. It is established after structural supervisions, that the investigated alloys crystallize in dendryte form and in centrifugal casting conditions have cooling rate sensivity and inclination to texture structure forming in outmost layer of casting. Phase composition of alloys corresponds to the results of thermodynamics calculations of the nonequilibrium crystallization conditions.

6

Selected the Casting Properties of the Composites AlMg10+Cgr

Łągiewka M.

Archives of Metallurgy and Materials

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2017

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Vol. 62, iss. 3

1585--1589

EN

The paper is a review of the previous investigations concerning the influence of graphite particles both on the casting properties of metal matrix composites (MMCs). The work presents the examination results of casting properties (i.e. castability and shrinkage) of the MMCs with matrices of a selected aluminium alloy reinforced with graphite particles. There is also presented the influence of graphite particles on the surface tension and viscosity of the flowing and filling the mould composite suspension. The suspensions containing various percentages of graphite particles (namely 5%, 10%, or 15% in volume) were prepared in order to perform the above mentioned examinations. Castability (fluidity) of these suspensions was measured in two ways, i.e. by means of both the spiral test and the rod test, while their shrinkage was determined with the use of a device designed and assembled in the Department of Foundry Engineering, CUT. The device enables to determine changes in the length of a casting during its solidification with respect to the specified length of the test rod. The surface tension was determined by the wedge casting method consisting in the pouring of metal into an open shell mould with the cavity of wedge geometry, the sharp edge being perpendicular to the free metal surface. The change in viscosity corresponding to the change in graphite particles percentage was calculated from Einstein’s equation. The results of examinations show that the introduction of reinforcing graphite particles results in both a significant increase in the viscosity of the flowing suspension and a considerable decrease in its castability. The greater dimensional stability of castings was observed, i.e. the shrinkage of composite castings was smaller than the shrinkage of matrix alloy itself. An increase in surface tension index value with an increase in volume percentage of graphite particles in composite was also noticed.

7

ThermoCalc Application for the Assessment of Binary Alloys Non-Equilibrium Solidification

Zyska A., Konopka Z., Łągiewka M., Kordas P.

Archives of Foundry Engineering

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2017

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Vol. 17, iss. 1

163--168

EN

The paper presents the possibility of application of the developed computer script which allows the assessment of non-equilibrium solidification of binary alloys in the ThermoCalc program. The script makes use of databases and calculation procedures of the POLY-3 module. A solidification model including diffusion in the solid state, developed by Wołczyński, is used to describe the non-equilibrium solidification. The model takes into account the influence of the degree of solute segregation on the solidification process by applying the so-called back-diffusion parameter. The core of the script is the iteration procedure with implemented model equation. The possibility of application of the presented calculation method is illustrated on the example of the Cr-30% Ni alloy. Computer simulations carried out with use of the developed script allow to determine the influence of the back-diffusion parameter on the course of solidification curves, solidus temperature, phase composition of the alloy and the fraction of each phase after the solidification completion, the profile of solute concentration in liquid during solidification process, the average solute concentration in solid phase at the eutectic temperature and many other quantities which are usually calculated in the ThermoCalc program.

8

The Influence of Home Scrap on Porosity of MgAl9Zn1 Alloy Pressure Castings

Konopka Z., Chojnacki A., Łągiewka M., Zyska A.

Archives of Foundry Engineering

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2017

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Vol. 17, iss. 1

99--102

EN

The work presents the results of examinations concerning the influence of various amounts of home scrap additions on the porosity of castings made of MgAl9Zn1 alloy. The fraction of home scrap in the metal charge ranged from 0 to 100%. Castings were pressure cast by means of the hot-chamber pressure die casting machine under the industrial conditions in one of the domestic foundries. Additionally, for the purpose of comparison, the porosity of specimens cut out directly of the MgAl9Zn1 ingot alloy was also determined. The examinations consisted in the qualitative assessment of porosity by means of the optical microscopy and its quantitative determination by the method of weighting specimens in air and in water. It was found during the examination that the porosity of castings decreases with an increase in the home scrap fraction in the metal charge. The qualitative examinations confirmed the beneficial influence of the increased home scrap fraction on the porosity of castings. It was concluded that the reusing of home scrap in a foundry can be a good way of reduction of costs related to the production of pressure castings.

9

The Influence of Home Scrap on Mechanical Properties of MgAl9Zn1 Alloy Castings

Konopka Z., Chojnacki A. C., Łągiewka M., Zyska A.

Archives of Foundry Engineering

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2017

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Vol. 17, iss. 2

39--42

EN

The work presents the results of examinations concerning the influence of various amounts of home scrap additions on the properties of castings made of MgAl9Zn1 alloy. The fraction of home scrap in the metal charge ranged from 0 to 100%. Castings were pressure cast by means of the hot-chamber pressure die casting machine under the industrial conditions in one of the domestic foundries. The examinations consisted in the determination of the following properties: tensile strength Rm, yield strength Rp0.2, and the unit elongation A5, all being measured during the static tensile test. Also the hardness measurements were taken by the Brinell method. It was found that the mechanical properties (mainly the strength properties) are being improved up to the home scrap fraction of 50%. Their values were increased by about 30% over this range. Further rise in the home scrap content, however, brought a definite decrease in these properties. The unit elongation A5 exhibited continual decrease with an increase in the home scrap fraction in the metal charge. A large growth of hardness was noticed for the home scrap fraction increasing up to the value of 50%. Further increasing the home scrap percentage, however, did not result in a significant rise of the hardness value any more.

10

Modelling of the Dendritic Crystallization by the Cellular Automaton Method

Zyska A., Konopka Z., Łągiewka M., Nadolski M.

Archives of Foundry Engineering

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2016

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Vol. 16, iss. 1

99--106

EN

A numerical model of binary alloy crystallization, based on the cellular automaton technique, is presented. The model allows to follow the crystallization front movement and to generate the images of evolution of the dendritic structures during the solidification of a binary alloy. The mathematic description of the model takes into account the proceeding thermal, diffusive, and surface phenomena. There are presented the results of numerical simulations concerning the multi-dendritic growth of solid phase along with the accompanying changes in the alloying element concentration field during the solidification of Al + 5% wt. Mg alloy. The model structure of the solidified casting was achieved and compared with the actual structure of a die casting. The dendrite interaction was studied with respect to its influence on the generation and growth of the primary and secondary dendrite arms and on the evolution of solute segregation both in the liquid and in the solid state during the crystallization of the examined alloy. The morphology of a single, free-growing dendritic crystal was also modelled. The performed investigations and analyses allowed to state e.g. that the developed numerical model correctly describes the actual evolution of the dendritic structure under the non-equilibrium conditions and provides for obtaining the qualitatively correct results of simulation of the crystallization process.

11

Rola obiektów hydrotechnicznych na obszarach objętych ochroną przyrody

Łągiewka M., Opyrchał L., Wanat M.

Przegląd Naukowy Inżynieria i Kształtowanie Środowiska

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2015

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Vol. 24, No. 3

249--256

PL

Elektrownie wodne to czyste ekologicznie i niepowodujące zanieczyszczenia atmosfery instalacje wytwarzające energię elektryczną. Ważnym elementem elektrowni wodnych są zbiorniki retencyjne, gromadzące wodę na potrzeby energetyki. Powszechnie zostało przyjęte, iż powstawanie owych zbiorników jest jednoznaczne z degradacją funkcjonujących ekosystemów rzecznych. Jednak okazuje się, że dzięki zbiornikom retencyjnym powstają nowe ekosystemy, umożliwiające rozwój fauny i fl ory. W artykule przeanalizowano wpływ obiektów hydrotechnicznych na obszary objęte ochroną przyrody w Polsce. Przedstawiane wyniki badań dają rzeczywisty obraz wpływu stworzonych przez człowieka zbiorników wodnych na stan środowiska przyrodniczego.

EN

Hydropower is a pro-ecological method of producing ecofriendly electricity, which priority should be the accordance of leaded activities with the applicable environmental regulations. Important activity related to the hydroelectric power stations is the creation of water reservoirs, which provide the adequate maintenance of groundwater levels and flood mitigation by minimizing the water risings, what in consequence reflects in less environmental losses. It has been generally accepted that the development of human civilization is essentially related to the degradation and deterioration in the functioning of individual nature elements. However, it turns out that the development can contribute to the creation of entirely new areas, in which it will become possible to restore properly functioning ecosystems.

12

The Influence of Remelting on the Quality of Prosthetic Cobalt Alloys

Nadolski M., Łągiewka M., Konopka Z., Zyska A., Golański G.

Archives of Foundry Engineering

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2015

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Vol. 15, iss. 3 spec.

53--58

EN

A commercial cobalt alloy applied in dental prosthetics was investigated. The scope of the work included the microstructure analysis, performance examination (tensile strength, microhardness, corrosion resistance), and dilatometric examination. The investigated alloy after a single remelting was characterised by higher tensile strength and hardness. There were not found the definite results with regard to the corrosion resistance of the examined materials. No significant change occurred in the coefficient of thermal expansion.

13

The Influence of Pressure Die Casting Parameters on the Castability of AlSi11-SiCp Composites

Konopka Z., Zyska A., Łągiewka M., Nadolski M.

Archives of Foundry Engineering

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2015

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Vol. 15, iss. 1

29--34

EN

The paper presents the method of preparing a composite slurry composed of AlSi11 alloy matrix and 10 vol.% of SiC particles, as well as the method of its high-pressure die casting and the measurement results concerning the castability of the obtained composite. Composite castings were produced at various values of the piston velocity in the second stage of injection, diverse intensification pressure values, and various injection gate width values. There were found the regression equations describing the change of castability of the examined composite as a function of pressure die casting process parameters. The conclusion gives the analysis and the interpretation of the obtained results.

14

The Influence of Graphite Type on the Abrasive Wear of AlMg10 Matrix Composites

Łągiewka M., Konopka Z., Zyska A., Nadolski M.

Archives of Foundry Engineering

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2015

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Vol. 15, iss. 1 spec.

65--68

EN

The presented work discuss the influence of various types of graphite additions on the abrasive wear of AlMg10 matrix alloy composites. Flake graphite, electrographite, and short graphite fibre were used as a composite reinforcement. Composites containing 10 vol. % of graphite particles were produced by mechanical mixing of the liquid alloy with simultaneous introduction of the reinforcement. Composite suspensions were gravity cast into metal moulds. The achieved castings were tested for the abrasive wear. Also the pure matrix alloy was examined. Microphotographs of the produced materials were taken, the specimens were also examined after the abrasion test by observing the microsections perpendicular to the abraded surface. The carried out experiments allow to state that even the little addition of graphite influences beneficially the tribological properties of composite under small loads applied to the frictional pair. It was found that under the increased load (30 N) the least abrasive wear is exhibited by the composite reinforced with graphite fibre, the largest one occurring for the composite reinforced with electrographite. The composite reinforced with electrographite, however, exhibited the mass loss less by 25% than the pure matrix alloy.

15

Properties of AlSi9Mg Alloy Matrix Composite Reinforced with Short Carbon Fibre after Remelting

Łągiewka M., Konopka Z.

Archives of Foundry Engineering

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2015

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Vol. 15, iss. 3

39--42

EN

The presented work describes the results of examination of the mechanical properties of castings made either of AlSi9Mg alloy matrix composite reinforced with short carbon fibre or of the pure AlSi9Mg alloy. The tensile strength, the yield strength, Young’s modulus, and the unit elongation were examined both for initial castings and for castings made of the remelted composite or AlSi9Mg alloy. After preparing metallographic specimens, the structure of the remelted materials was assessed. A few non-metallic inclusions were observed in the structure of the remelted composite, not occurring in the initial castings. Mechanical testing revealed that all the examined properties of the initial composite material exceed those of the non-reinforced matrix. A decrease in mechanical properties was stated both for the metal matrix and for the composite after the remelting process, but this decrease was so slight that it either does not preclude them from further use or does not restrict the range of their application.

16

Porosity of Castings Produced by the Vacuum Assisted Pressure Die Casting Method

Zyska A., Konopka Z., Łągiewka M., Nadolski M.

Archives of Foundry Engineering

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2015

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Vol. 15, iss. 1

125--130

EN

The paper presents the results of investigations concerning the influence of negative (relative) pressure in the die cavity of high pressure die casting machine on the porosity of castings made of AlSi9Cu3 alloy. Examinations were carried out for the VertaCast cold chamber vertical pressure die casting machine equipped with a vacuum system. Experiments were performed for three values of the applied gauge pressure: -0.3 bar, -0.5 bar, and -0.7 bar, at constant values of other technological parameters, selected during the formerly carried initial experiments. Porosity of castings was assessed on the basis of microstructure observation and the density measurements performed by the method of hydrostatic weighing. The performed investigation allowed to find out that – for the examined pressure range – the porosity of castings decreases linearly with an increase in the absolute value of negative pressure applied to the die cavity. The negative pressure value of -0.7 bar allows to produce castings exhibiting porosity value less than 1%. Large blowholes arisen probably by occlusion of gaseous phase during the injection of metal into the die cavity, were found in castings produced at the negative pressure value of -0.3 bar. These blowholes are placed mostly in regions of local thermal centres and often accompanied by the discontinuities in the form of interdendritic shrinkage micro-porosity. It was concluded that the high quality AlSi9Cu3 alloy castings able to work in elevated temperatures can be achieved for the absolute value of the negative pressure applied to the die cavity greater than 0.5 bar at the applied set of other parameters of pressure die casting machine work.

17

Periodogram jako metoda interpretacji wyników pomiarów z monitoringu obiektów hydrotechnicznych

Opyrchał L., Wanat M., Łągiewka M.

Logistyka

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2014

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nr 4

4746--4755, CD6

PL

W pracy przedstawiono klasyfikację pomiarów kontrolnych wykonywanych na zaporze Solina. W tym celu zastosowano statystyczną metodę periodogramu. Analizie poddano pomiary ze szczelinomierzy trójosiowych rozmieszczonych na dylatacjach pomiędzy sekcjami zapory. W wyniku otrzymano zbiór periodogramów, które zostały podzielone na cztery typy. Typy otrzymanych periodogramów zależą od rodzajów zjawisk wywołujących przemieszczenie budowli. Metoda periodogramu może służyć do szybkiego określania, które ze zjawisk mają decydujący wpływ na przemieszczenie badanego punktu zapory.

EN

The paper presents a classification of control measurements made on Solina dam. For this purpose a periodogram statistical method is applied. We analyzed measurements of triaxial feeler located at the joint between sections of the dam. The result was a set of periodograms, which are classified into three types. Periodograms classes depend on the types of events that cause displacement. Periodogram method can be used to determine quickly which event have a decisive impact on the displacement of the tested dam.

18

Mechanical and Tribological Properties of Metal Matrix Composites Reinforced with Short Carbon Fibre

Łągiewka M.

Archives of Metallurgy and Materials

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2014

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Vol. 59, iss. 2

707--711

EN

The paper constitutes the culmination of the foregoing investigations concerning the influence of short carbon fibre on the enhancement of AlMg10 alloy properties. The presented work brings forward the results of examinations of mechanical and tribological properties of metal matrix composites (MMCs) based on this alloy. Composites were produced by two methods: either by gravity casting or by squeeze casting in semi-solid state of a composite suspension previously obtained through mixing of its components. The volume fraction of the reinforcing phase varied and took the value of 5, or 10, or finally 15 vol. %. Specimens cut out of the experimental castings were examined with respect both to their mechanical properties, i.e. the tensile strength and unit elongation, and to their tribological behaviour. A series of examinations of the mechanical properties proved a slight increase in tensile strength and a minor decrease in unit elongation of the examined composite materials both for gravity cast and squeeze cast specimens, as compared with the properties of pure matrix alloy. The introduction of short carbon fibre into the matrix alloy resulted also in the increased abrasive wear resistance of the examined composites in comparison to the non-reinforced matrix.

PL

Artykuł stanowi podsumowanie dotychczasowych badań na temat wpływu krótkich włókien węglowych na poprawę właściwości stopu AlMg10. W prezentowanej pracy przedstawiono wyniki badań właściwości mechanicznych i trybologicznych kompozytów metalowych. Kompozyty zostały wytworzone dwoma metodami: poprzez odlewanie grawitacyjne wytworzonej uprzednio na drodze mieszania zawiesiny kompozytowej oraz poprzez prasowanie w stanie ciekło-stałym tejże zawiesiny o zmiennym udziale objętościowym krótkich włókien węglowych. Ilość zbrojenia wynosiła odpowiednio 5.10 i 15% obj. Badania właściwości mechanicznych polegały na określeniu wytrzymałości na rozciąganie badanych materiałów oraz wydłużenia. Po przeprowadzeniu szeregu badań właściwości mechanicznych kompozytów wykazano nieznaczny wzrost wytrzymałości na rozciąganie oraz spadek wydłużenia kompozytów w porównaniu z właściwościami stopu osnowy zarówno w przypadku próbek prasowanych jaki i odlewanych grawitacyjnie. Wprowadzenie krótkich włókien węglowych do osnowy ze stopu AlMglO spowodowało również zmniejszenie zużycia ściernego badanych kompozytów w porównaniu z nieuzbrojoną osnową.

19

The Influence of the Mould Filling Conditions on the Quality of Castings Made of EN AC-44000 Alloy

Nadolski M., Konopka Z., Łągiewka M., Zyska A.

Archives of Foundry Engineering

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2014

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Vol. 14, iss. 2

19--22

EN

The work deals with the influence of change in the filling conditions of the ceramic moulds with plaster binder on the presence of gaseous porosity and the microstructure of the achieved test castings with graded wall thickness. Castings made of EN AC-44000 alloy, produced either by gravity casting, or by gravity casting with negative pressure generated around the mould (according to the Vacumetal technology), or by counter-gravity casting were compared. The results of examinations concerning the density of the produced castings indicate that no significant change in porosity was found. The increased size of silicon crystals was found for the increased wall thicknesses due to the slower cooling and solidification of castings.

20

The Influence of the Method of Mould Filling on the Quality of Castings Made of EN AC-44000 or EN AC-46200 Alloy

Nadolski M., Konopka Z., Łągiewka M., Zyska A.

Archives of Foundry Engineering

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2014

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Vol. 14, iss. 4

73--76

EN

The performed examinations concerning the process of filling the plaster ceramic moulds with aluminium alloys allowed to assess the influence of various methods of introducing the metal into the mould cavity on the macro- and microstructure of the obtained experimental castings. The comparison was performed for castings with graded wall thickness made either of EN AC-44000 alloy or of EN AC-46000 alloy, produced either by gravity casting, or by gravity casting with negative pressure generated around the mould (according to the Vacumetal technology), or by counter-gravity casting. It was found that the silicon crystals grow in size with an increase in wall thickness due to the slower cooling and solidification of castings.