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1
Content available Microstructural characterisation of Co-Cr-Mo casting dental alloys
Szala M., Beer-Lech K., Gancarczyk K., Kilic O., Pędrak P., Özer A., Skic A.
Advances in Science and Technology. Research Journal
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2017
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Vol. 11, no 4
76--82
EN
The study compares the microstructure of three commercial dental cobalt matrix alloys with related chemical composition declared by the manufacturer. Casts were produced with lost wax method, then melted and casted with centrifugal induction casting machine. The Co-Cr-Mo alloys were casted according to the manufacturers procedure. The samples’ chemical composition and phase composition, respectively, using WDXRF (Wavelength Dispersive X-Ray Fluorescence) and XRD (X-ray Diffarction) methods were analysed. Casts microstructure by mean of LOM (Light Optical Microscopy), SEM (Scanning Electron Microscopy) and EDS (Energy Dispersive X-ray Spectroscopy) were investigated. Vickers hardness HV10 was measured. Quantitative microstructure evaluation was performed by means of computer image processing. The results of the chemical composition indicate the high stability of the chemical composition for alloy A. In case of alloys B and C, there was a significant difference in carbon content. Quantitative differences in image of microstructure between of castings A and B, C were noticed. The greater amount of precipitates was recorded for castings with higher carbon content. In all investigated castings, the presence of β matrix solution and M23C6 carbide precipitations was found.
2
Content available Dendritic Structure Analysis of CMSX-4 Cored Turbine Blades Roots
Krawczyk J.
Archives of Metallurgy and Materials
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2016
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Vol. 61, iss. 2B
1129--1134
EN
The microstructure of as-cast cored turbine blades roots, made of the single-crystal CMSX-4 nickel-based superalloy was investigated. Analysed blades were obtained by directional solidification technique in the industrial ALD Bridgman induction furnace. The investigations of the microstructure of blades roots were performed using SEM and X-ray techniques including diffraction topography with the use of Auleytner method. Characteristic shapes of dendrites with various arrangement were observed on the SEM images taken from the cross-sections, made transversely to the main blades axis. The differences in quality of the structure in particular areas of blades roots were revealed. Based on the results, the influence of cooling bores on blades root structure was analysed and the changes in the distribution and geometry of cooling bores were proposed.
3
Content available Poprawa jakości wewnętrznej wlewka konwencjonalnego metodą obróbki akustycznej
Kania H., Nowacki K.
Prace Instytutu Metalurgii Żelaza
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2015
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T. 67, nr 2
38--43
PL
Bezpośrednim efektem oddziaływania energii akustycznej podczas krzepnięcia wlewka we wlewnicy jest zmiana struktury metalu. Dotychczasowe badania i eksperymenty przeprowadzone w ramach współpracy naukowej pomiędzy Politechnikę Śląską w Katowicach i Instytutem Metalurgii Żelaza w Gliwicach nad zastosowaniem technologii obróbki akustycznej do poprawy jakości wewnętrznej wlewków ze stali wysokowęglowej dały pozytywne wyniki. W strefie oddziaływania fali akustycznej we wlewku, uzyskano rozdrobnienie struktury stali i równomierny rozkład pierwiastków, a także wzrost twardości, która może być postrzegana jako wskaźnik obrabialności akustycznej stali. W celu określenia przydatności opracowanej technologii w warunkach przemysłowych, zawiązano konsorcjum składające się z partnerów polskich i niemieckich. Liderem konsorcjum jest grupa przemysłowa Alchemia S.A. (Huta Batory), ponadto w jego składzie znajdują się następujący partnerzy: Politechnika Śląska Katowice, Instytut Metalurgii Żelaza z Gliwic, TU Bergakademie Freiberg, BGH Edelstahl Freital GmbH oraz wrocławska firma PBP OPTEL S.A. Założonym efektem prowadzonych badań jest redukcja segregacji pierwiastków w objętości wlewka konwencjonalnego oraz zwiększenie udziału strefy kryształów równoosiowych za pomocą fali akustycznej dostarczonej bezpośrednio do objętości ciekłego, krzepnącego wlewka, a poprzez to poprawa właściwości fizycznych przerobionego plastycznie materiału.
EN
The direct effect of exposure to acoustic energy during the solidification of ingot in a mould is the change in metal structure. The research and experiments carried out so far as a part of scientific cooperation on application of the acoustic treatment technology for improving the internal homogeneity of high-carbon steel ingots between the Silesian University of Technology in Katowice and the Institute for Ferrous Metallurgy in Gliwice yielded positive results. Within the acoustic wave influence area in the ingot, the refinement of steel structure and uniform distribution of elements as well as increase in hardness, which can be perceived as the steel acoustic treatability index, were obtained. To determine the applicability of the developed technology under industrial conditions, the consortium consisting of Polish and German partners has been set up. The leader of the consortium is the industrial group Alchemia S.A. (Huta Batory). In addition, it comprises the following partners: Silesian University of Technology in Katowice, Institute for Ferrous Metallurgy in Gliwice, TU Bergakademie Freiberg, BGH Edelstahl Freital GmbH and PBP OPTEL S.A. in Wroclaw. The assumed effect of conducted research is the reduction in segregation of elements within the volume of conventional ingot and increase in the share of the area of equiaxed crystals by means of the acoustic wave supplied directly to the volume of solidifying liquid ingot, and thus the improvement in physical properties of plastically worked material.
4
Content available Modeling of two-stage solidification: Part II computational verification of the model
Wodo O., Gawrońska E.
Archives of Foundry Engineering
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2013
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Vol. 13, iss. 1
125--130
EN
In Part I of this article, two-stage solidification model was presented. In this part we use our model to simulate solidification of the Al 7% Si alloy for two cooling rates - 2 deg/s and - 20 deg/s. Simulations have been performed for two eutectic transformation modes, typical for modified and unmodified alloys. Obtained cooling curves are qualitatively consistent with the typical cooling curves for modified and unmodified alloys. Moreover, evolution of cooling-curve characteristics is compared with the analytical model and found to be in close agreement.
5
Content available Modeling of two-stage solidification: Part I model development
Wodo O., Gawrońska E.
Archives of Foundry Engineering
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2012
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Vol. 12, iss. 4
151-156
EN
The paper presents a new numerical model of solidification processes in hypoeutectic alloys. The model combines stochastic elements, such as e.g. random nucleation sites and orientation of dendritic grains, as well as deterministic methods e.g. to compute velocity of dendritic tips and eutectic grains. The model can be used to determine the temperature and the size of structure constituents (of both, the primary solid phase and eutectics) and the arrangement of individual dendritic and eutectic grains in the consecutive stages of solidification. Two eutectic transformation modes, typical to modified and unmodified hypoeutectic alloys, have been included in the model. To achieve this, cellular automata and Voronoi diagrams have been utilized.
6
Content available remote A concast billet caster and electromagnetic stirring of the melt
Stransky K., Kavicka F., Sekanina B., Stetina J., Dobrovska J., Stransky L.
Prace Instytutu Metalurgii Żelaza
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2009
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T. 61, nr 5
142-145
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.
7
Content available remote Zmiany mikrostruktury i wydzieleń węglików w staliwie Cr-Ni po długotrwałej eksploatacji
Zapała R., Głownia J., Mikułowski B.
Archiwum Odlewnictwa
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2003
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R. 3, nr 8
209--214
PL
Zbadano morfologię wydzieleń węglików w materiale pochodzącym z rur, które pracowały w konwertorze instalacji do produkcji gazu syntetycznego. Odlewane odśrodkowo rury wykonano z dwóch gatunków staliwa Cr25-Ni35-Nb oraz Cr24-Ni24-Nb. Określono zmiany zachodzące w mikrostrukturze tych stopów pod wpływem wysokiej temperatury i środowiska pracy, a także koagulację węglików na grubości ścianek rur.
EN
Morphology of carbides precipitation was observed in centrifugal tube castings for installation of synthetic gas. The tubes have been made of Cr25-Ni35-Nb and Cr24-Ni24-Nb steel. Influence of temperature as well as conditions of operation on microstructure and coagulation of carbides has been investigated.
8
Content available remote Ocena fraktalna powierzchni krzepnięcia
Marek M.
Archiwum Odlewnictwa
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2003
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R. 3, nr 10
17--22
PL
Artykuł dotyczy możliwości zastosowania geometrii fraktalnej do opisu powierzchni krzepnięcia. Głównym przedmiotem badań są struktury dendrytyczne – zwrócono uwagę na ich samopodobieństwo i oszacowano wymiar fraktalny na wybranym przykładzie.
EN
Article deals with possibility of describing solidification surface using methods of fractal geometry. The main subject of interest are dendritic structures – their self-similarity is pointed out and fractal dimension of selected dendrite is estimated.
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