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1
Content available Ocena stopnia wyeksploatowania materiału wirników turbin parowych z niskostopowej stali Cr-Mo-V po eksploatacji w czasie znacznie przekraczającym czas obliczeniowy
Dziuba-Kałuża M., Dobrzański J., Purzyńska H., Kania-Pifczyk Z., Rozmus R.
Prace Instytutu Metalurgii Żelaza
|
2018
|
T. 70, nr 1
4--11
PL
Celem pracy była ocena stanu rozwoju procesów wydzieleniowych, wyznaczenie odpowiadającej mu pręd-kości pełzania i wyznaczenie odpowiadającego im stopnia wyczerpania badanych stali 23H2MF, 26H2MF oraz 21HMF po długotrwałej pracy w warunkach pełzania. Przeprowadzono identyfikację występujących wydzieleń w oparciu o ich obraz dyfrakcyjny. Wykonana została próba pełzania z pomiarem wydłużenia w czasie jej trwania dla wyznaczenia prędkości pełzania na materiale wirnika po eksploatacji znacznie poza ob-liczeniowym czasem pracy. Wykonano badania mikrostruktury w skaningowym mikroskopie elektronowym, wyznaczono skład fazowy węglików metodą rentgenowskiej analizy fazowej.
XX
The aim of the work was to assess the state of development of precipitation processes, determine the corresponding creep speed, and determine the corresponding degree of exhaustion of 23H2MF, 26H2MF and 21HMF steels after long-term work under creep conditions. The identification of precipitates based on their diffraction pattern was carried out. A creep test was performed with the measurement of elongation during its duration to determine the creep speed on the rotor material after use in time significantly exceeding its computational working time. Microstructure investigations were carried out using a scanning electron microscope, and phase composition of carbides was determined with the use of X-ray phase analysis.
2
Content available Residual Life of Boiler Pressure Parts Made of the 13CrMo4-5 Steel after Long-Term Operation in a Creep Conditions
Dziuba-Kałuża M., Zieliński A., Dobrzański J., Sroka M., Urbańczyk P., Śliwa A.
Archives of Metallurgy and Materials
|
2018
|
Vol. 63, iss. 2
889--897
EN
This paper presents the method for determination of the time of further safe service for welded joints of boiler components after exceeding the design work time. The evaluation of the life of the parent material and its welded joints was performed. Microstructure investigations using a scanning electron microscope, investigations of strength properties, impact testing, hardness measurements and abridged creep tests of the basic material and welded joints were carried out. The investigations described in this paper allowed the time of further safe service of the examined components made of 13CrMo4-5 steel to be determined. The method for determination of the time of safe service of boiler components working under creep conditions allows their operation beyond the design service life. The obtained results of investigations are part of the materials database developed by the Institute for Ferrous Metallurgy.
3
Content available Evaluation of Creep Strength of Heterogeneous Welded Joint in HR6W Alloy and Sanicro 25 Steel
Zieliński A., Dobrzański L., Purzyńska H., Sikora R., Dziuba-Kałuża M., Kania Z.
Archives of Metallurgy and Materials
|
2017
|
Vol. 62, iss. 4
2057--2064
EN
This article presents the results of investigations on HR6W alloy and Sanicro 25 steel and the dissimilar welded joint made of them. The characteristic images of microstructure of the investigated materials in the as-received condition and following the creep test, observed with a scanning electron microscope (SEM), are shown. The X-ray analysis of phase composition of the existing precipitates was carried out. The method for evaluation of creep strength based on abridged creep tests carried out at a temperature higher than the design one is presented. The obtained results do not deviate from the values of creep strength determined in long-term creep tests. The maximum difference in creep strength of the investigated materials is ±20%, which is in compliance with the acceptable scatter band. The methodology presented can be used for verification of creep strength (life time) of the material of finished components to be operated under creep conditions.
4
Content available remote The evaluation of suitability for operation of repair low-alloy steel welded joints
Dziuba-Kałuża M., Zieliński A., Jasiński A., Sroka M., Dobrzański J., Linek T.
Archives of Materials Science and Engineering
|
2016
|
Vol. 78, nr 2
78--86
EN
Purpose: The purpose of the work was to evaluate the material condition of repair welded joints of steam pipelines with regard to their suitability for operation including determination of the time of their further safe operation. Design/methodology/approach: The following was carried out: microstructure investigations using scanning electron microscopy, investigations on mechanical properties at room and elevated temperatures, determination of the fracture appearance transition temperature based on impact tests. The abridged creep tests without measurement of elongation during test were carried out to determine the material’s residual life. Findings: The time of safe operation was determined for welded joints made in 14MoV63 steel after long-term service and 14MoV63 steel after long-term service and in the as-received condition. Practical implications: The applied methodology and the adopted procedures are used in evaluating the condition and forecasting further operation of new repair welded joints for the pressure part components of power equipment working under creep conditions. Originality/value: The obtained results of investigations will be the elements of materials characteristics worked out by the Institute for Ferrous Metallurgy for the steels and welded joints made in them to work under creep conditions.
5
Content available Trwałość eksploatacyjna materiału elementów pracujących w warunkach pełzania w energetycznych urządzeniach wysokociśnieniowych
Dobrzański J., Zieliński A., Purzyńska H., Dziuba-Kałuża M., Matusik M.
Prace Instytutu Metalurgii Żelaza
|
2015
|
T. 67, nr 2
158--167
PL
Przedstawiono dobór rodzaju badań w zależności od czasu eksploatacji i rodzaju elementu dla oceny stanu materiału i prognozy trwałości eksploatacyjnej w energetycznych urządzeniach wysokociśnieniowych. Określono względne udziały procesów powodujących zmiany w strukturze materiału podczas pełzania w zależności od stopnia wyczerpania. Dokonano klasyfikacji zmian w strukturze w zależności od dostępności materiału z uszkodzeniami i bez uszkodzeń wewnętrznych. Badano zmiany w strukturze stali pracujących w warunkach pełzania, w tym klasę rozpadu perlitu / bainitu i/lub martenzytu, rozwoju procesów wydzieleniowych i rozwoju wewnętrznych uszkodzeń w zależności od stopnia wyczerpania. Metodologię oceny stanu badanych stali po eksploatacji w warunkach pełzania na podstawie oceny zmian w strukturze procesów składowych tzn.: zmian w strukturze perlitu, bainitu lub martenzytu, zmian w zakresie rozwoju procesów wydzieleniowych oraz zmian w zakresie rozwoju uszkodzeń wewnętrznych odniesionych do stopnia wyczerpania przedstawiono na przykładzie stali niskostopowych i stali X20CrMoV12-1. Poziom wybranych właściwości mechanicznych, twardość, temperaturę przejścia w stan kruchy w zależności od klasy struktury i odpowiadającego jej stopnia wyczerpania przedstawiono na przykładzie stali 14MoV6-3 i X20CrMoV12 -1 po długotrwałej eksploatacji w warunkach pełzania. Sporządzono wykresy resztkowej wytrzymałości na pełzanie w postaci zależności σb = f(LM) w zależności od klasy struktury i stanu rozwoju procesów wydzieleniowych węglików na przykładzie stali 13CrMo4-5. Wyznaczoną trwałość resztkową w zależności od czasu do zerwania w próbie pełzania od temperatury badania przy stałym poziomie naprężenia odpowiadającym eksploatacyjnemu przedstawiono w postaci zależności tr =f(T) dla σ = const na przykładzie stali X20CrMoV12-1. Zależność prędkości pełzania od naprężenia σ dla temperatury dalszej eksploatacji w zależności od klasy struktury i stanu rozwoju procesów wydzieleniowych węglików przedstawiono na przykładzie stali 13CrMo4 -5. Rodzaj i udział występujących węglików w zależności od klasy struktury i stopnia wyczerpania przestawiono na przykładzie stali 13CrMo4-5. Ocenę stanu materiału na podstawie badań mikrostruktury z zastosowaniem metody replik matrycowych przedstawiono na przykładzie materiału odcinka rurociągu pary świeżej ze stali 14MoV6-3 po 216 000 godzinach eksploatacji w warunkach pełzania.
EN
Selection of the type of investigations depending on service duration and type of element for the evaluation of material condition and forecasting the life time in high-pressure power units was presented. Relative shares of processes causing changes in structure of material during creep depending on the exhaustion degree were determined. Changes in structure depending on availability of the material with and without internal damages were classified. Changes in structure of the examined steels working under creep conditions, including the pearlite/bainite and martensite decomposition class, development of precipitation processes and development of internal damages depending on the exhaustion degree, were examined. Methodology for the evaluation of condition of the tested steels after service under creep conditions based on the assessment of structure changes in constituent processes, the so-called: changes in pearlite, bainite or martensite structure, changes in development of precipitation processes and changes in development of internal damages related to the exhaustion extent, was presented on the example of low-alloy steels and X20CrMoV12-1 steel. The level of selected mechanical properties, hardness, brittle fracture appearance transition temperature depending on the structure class and corresponding exhaustion degree was presented on the example of 14MoV6-3 and X20CrMoV12-1 steels after long-term service under creep conditions. The disposable creep strength diagrams were made in the form of relationship σb = f(LM) depending on the structure class and state of development of the carbide precipitation processes on the example of 13CrMo4-5 steel. The residual life determined as a relationship between time to rupture in the creep test and test temperature at constant stress level corresponding to the operating one is presented in the form of relationship tr = f(T) for σ = const on the example of X20CrMoV12-1 steel. The relationship between creep rate and stress σ for temperature of further service depending on the structure class and state of development of carbide precipitation processes was presented on the example of 13CrMo4-5 steel. The type and share of the occurring carbides depending on the structure class and exhaustion degree was presented on the example of 13CrMo4-5 steel. The evaluation of material condition based on investigations of microstructure using the matrix replica method was presented on the example of the material of 14MoV6-3 steel primary steam pipeline section after 216 000 h service under creep conditions.
6
Content available Badania nowych materiałów na elementy kotłów o nadkrytycznych parametrach pracy
Dobrzański J., Zieliński A., Purzyńska H., Dziuba-Kałuża M.
Prace Instytutu Metalurgii Żelaza
|
2015
|
T. 67, nr 2
106--111
PL
Celem pracy było przedstawienie wybranych charakterystyk materiałowych dotyczących zmian właściwości wytrzymałościowych odniesionych do zmian strukturalnych zachodzących w stali podczas długotrwałej eksploatacji w warunkach pełzania. W opracowaniu mającym charakter przeglądowy zawarte zostały dane dotyczące stali stosowanych do budowy kotłów nadkrytycznych. Przedstawiono wybrane wyniki badań stali T23 (7CrWVMoNb9-6), T24 (7CrMoVTiB10-10), P91 (X10CrMoVNb9-1), P92 (X10CrWMoVNb9-2) VM12 (X12CrCoWVNb12-2-)2 w stanie wyjściowym oraz po długotrwałej ekspozycji w warunkach pełzania.
EN
The purpose of the paper was to present selected material characteristics with regard to changes in strength properties related to structural changes occurring in steel during long-term service under creep conditions. This review includes data concerning steels used for construction of supercritical boilers. Selected test results are presented for T23 (7CrWVMoNb9-6), T24 (7CrMoVTiB10-10), P91 (X10CrMoVNb9-1), P92 (X10CrWMoVNb9-2) and VM12 (X12CrCoWVNb12-2-)2 steels in initial state and after long-term exposure under creep conditions.
7
Content available remote Residual life of the (15HM) 13CrMo4-5 steel after 250 000 h service demonstrating internal damages in the form of voids
Dziuba-Kałuża M., Zieliński A., Dobrzański J., Sroka M.
Archives of Materials Science and Engineering
|
2015
|
Vol. 73, nr 1
25--32
EN
Purpose: The purpose of the paper was to evaluate the material condition of the (15HM) 13CrMo4-5 steel after 250 000 h service under creep conditions demonstrating internal damages in the form of voids. Design/methodology/approach: The investigations of microstructure using the scanning electron microscopy and investigations of mechanical properties at room and elevated temperature were carried out. The brittle fracture appearance transition temperature was determined based on impact tests. Findings: The influence of long-term service under creep conditions on mechanical properties and structure degradation of 13CrMo4-5 steel was determined. Practical implications: The applied methodology and adopted practice will be used for evaluation of condition and estimation of further operation of elements in the pressure part of power equipment working under creep conditions. Originality/value: The obtained results of investigations are the elements of material characteristics developed by the Institute for Ferrous Metallurgy in Gliwice (Poland) for steels working under creep conditions.
8
Content available remote The impact of repair welded joint on the life of Cr-Mo-V steel steam pipeline after service under creep conditions
Zieliński A., Dziuba-Kałuża M., Dobrzański J., Sroka M.
Archives of Materials Science and Engineering
|
2014
|
Vol. 68, nr 1
36--44
EN
Purpose: The purpose of this paper was to examine the impact of repair welded joints on the life time of primary steam pipelines after more than 200 000 h service under creep conditions. Design/methodology/approach: The investigations of microstructure using scanning microscopy, investigations of mechanical properties at room and elevated temperature, determination of brittle fracture appearance transition temperature based on impact strength tests and abridged creep tests were carried out in order to determine the residual life of the material. Findings: The completed investigations allowed the time of further safe operation of the elements of primary steam pipeline with repair welded joint to be determined in relation to the parent material and welded joint after service. Practical implications: The assessment of residual life and disposable residual life, and thus the estimation or determination of possible time of further safe operation, is of the essence in case of operating the elements much beyond the design work time. Originality/value: The obtained results of investigations are the elements of material characteristics developed by the Institute for Ferrous Metallurgy for steels and welded joints made from them working under creep conditions.
9
Content available remote The evaluation of suitability for operation of low-alloy Cr-Mo and Cr-Mo-V steel welded joints beyond the design work time
Dziuba-Kałuża M., Zieliński A., Dobrzański J., Sroka M.
Archives of Materials Science and Engineering
|
2014
|
Vol. 66, nr 1
21--30
EN
Purpose: The purpose of this paper was to develop material characteristics for homogeneous circumferential welded joints in low-alloy steel steam pipelines of power units after long-term service beyond the design work time. Design/methodology/approach: The investigations of microstructure using scanning microscopy, investigations of mechanical properties at room and elevated temperature, in particular the static tensile test, determination of brittle fracture appearance transition temperature based on the impact strength tests and abridged creep tests without measurement of elongation during test were carried out in order to determine the residual life of the material. Findings: The influence of long-term service on mechanical properties and structure of 13CrMo4-5 and 14MoV6-3 steel circumferential welded joints after long-term service under creep conditions beyond the design work time was determined. Practical implications: The applied methodology and adopted procedures will be used for evaluation of condition and prediction about further operation of welded joints of elements in the pressure part of power equipment working under creep conditions. Originality/value: The obtained results of investigations will be the elements of material characteristics developed by the Institute for Ferrous Metallurgy for steels and welded joints made from them working under creep conditions.
10
Content available remote Structure of welded joints of 14MoV6-3 and 13CrMo4-5 steel elements after design work time under creep conditions
Zieliński A., Dobrzański J., Dziuba-Kałuża M.
Archives of Materials Science and Engineering
|
2013
|
Vol. 61, nr 2
69--76
EN
Purpose: This paper is to present changes in the structure of material of 14MoV6-3 and 13CrMo4-5 alloyed steel components of power station boiler after long-term creep service. Design/methodology/approach: The investigated materials were obtained from Polish power stations. All the examined elements have exceeded their assessed life of 100 000 hours. The structural investigations were carried out on materials after long-term service under creep conditions. The microstructure was observed using light and scanning electron microscope. The investigations on the development of precipitation processes were done by X-ray diffraction phase analysis. Findings: Carbide precipitation evolution in correlation to the life exhaustion extent was presented. Practical implications: The presented methods can be used for evaluation of materials working under creep conditions. Originality/value: The presented results on changes in the structure and precipitation processes are applied to evaluation of the condition of elements in further industrial service.
11
Content available remote Mechanical properties of Cr-Mo and Cr-Mo-V low-alloy steel welded joints after long-term service under creep conditions
Dziuba-Kałuża M., Dobrzański J., Zieliński A.
Archives of Materials Science and Engineering
|
2013
|
Vol. 63, nr 1
5--12
EN
Purpose: The purpose of this paper was to evaluate mechanical properties of 13CrMo4-5 and 14MoV6-3 steel homogeneous circumferential welded joints after long-term service under creep conditions much beyond the design work time of 100,000 hours and their suitability for further service. Design/methodology/approach: Mechanical properties of individual elements of welded joints in non-destructive tests were determined. In particular, the brittle fracture appearance transition temperature as well as strength and plastic properties at room and elevated temperature were determined. Findings: The influence of long-term service on strength and plastic properties and on impact strength of tested material of 13CrMo4-5 and 14MoV6-3 steel homogeneous circumferential welded joints after long-term service under creep conditions beyond the design work time was determined. Research limitations/implications: The evaluation of suitability of the applied test methods in extension of service period for materials of welded joints of elements working under creep conditions after having exceeded the design work time was made. Practical implications: The obtained test results are used in creation of materials characteristics to allow predicting the life time of tested steels and their welded joints and are used for condition assessment and prediction about further operation of welded joints of elements in the pressure part of power equipment working under creep conditions. Originality/value: The applied methodology and developed materials characteristics are used for condition assessment and prediction about further safe operation of welded joints of elements in the pressure part of power equipment working under creep conditions.
12
Content available Statistical analysis using multiple regression of stereological parameters for skeleton castings microstructure
Cholewa M., Dziuba-Kałuża M.
Archives of Foundry Engineering
|
2011
|
Vol. 11, iss. 3 spec.
43--48
EN
In this article authors showed influence of technological parameters and modification treatment on structural properties for closed skeleton castings. Approach obtained maximal refinement of structure and minimal structure diversification. Skeleton castings were manufactured in accordance with elaborated production technology. Experimental castings were manufactured in variables technological conditions: range of pouring temperature 953÷1013 K , temperature of mould 293÷373 K and height of gating system above casting level 105÷175 mm. Analysis of metallographic specimens and quantitative analysis of silicon crystals and secondary dendrite-arm spacing analysis of solution α were performed. Average values of stereological parameters for all castings were determined. (B/L) and (P/A) factors were determined. On basis results of microstructural analysis authors compares research of samples. The aim of analysis was selected samples on least diversification of refinement degree of structure and least silicon crystals. On basis microstructural analysis authors state that samples 5 (AlSi11, Tpour 1013K, Tmould 333K, h – 265 mm) has the best structural properties (least diversification of refinement degree of structure and the least refinement of silicon crystals). Then statistical analysis results of structural analysis was obtained. On basis statistical analysis autors state that the best structural properties for technological parameters: Tpour = 1013 K, Tmould = 373 K and h = 230 mm [4]. The results of statistical analysis are the prerequisite for optimization studies.
13
Content available remote Kompozyty na bazie polimeru siarkowego ze szkieletowym wzmocnieniem AlSi
Cholewa M., Dziuba-Kałuża M.
Kompozyty
|
2009
|
R. 9, nr 1
73-77
PL
Przedstawiono metodę wykonania kompozytowych elementów zbudowanych z zamkniętych odlewów szkieletowych ze stopów AlSi z wypełnieniem polimerowo-ceramicznym. Wypełnienie polimerowe stanowiła polimerowa osnowa SULCEM® z ziarnistym wypełnieniem mineralnym, dając polimerowy, siarkowy beton SULBET®. Wzmacniające próbne odlewy szkieletowe wykonano w zmiennych warunkach technologicznych: temperatura zalewania 983 oraz 1013 K, temperatura formy 293 oraz 333 K przy stałej wysokości układu wlewowego na poziomie 265 mm. W celu określenia wytrzymałości na ściskanie przeprowadzono badania na próbkach z odlewu kompozytowego, z betonu polimerowego oraz na próbkach z samego szkieletu aluminiowego. Zaobserwowano liniową zależność naprężenia ściskającego od odkształcenia względnego dla próbek z kompozytu oraz z osnowy polimerowej. Próbki z polimerowego betonu siarkowego pod działaniem maksymalnej siły ulegają pękaniu kruchemu. Natomiast w przypadku próbek z kompozytu szkielet aluminiowy ogranicza kruche pękanie betonu. W próbkach kompozytowych uzyskano znaczne zwiększenie wytrzymałości na ściskanie w porównaniu do próbek osnowy i wzmocnienia. Określono warunki wytwarzania odlewów próbnych szkieletowych, zapewniających korzystne własności wytrzymałościowe kształtek kompozytowych.
EN
In article method of manufacturing composite elements was shown. The composite elements was constructed with closed skeleton casting and polymer - ceramic filler. AlSi alloys with antimony were used for manufacturing the closed skeleton castings. Polymer warp SULCEM® and seediness mineral filler were created polymer, sulfuric concrete SULBET®. Sulfuric concrete, which was filled aluminium skeletons very good mechanical properties was characterized (for specialist solutions compression strenght is Rc = 73-86 MPa, whereas bending strenght is Rg = 10-15 MPa), excellent corrosion resistance, fast-ness to acid, fastness oil, minicipal wastes resistance and very low absorbability. Al-Si alloys with antimony were used for manufacturing the reinforcement skeletons. Antimony belong to the group of chemical elements which modify structure of Al-Si alloys. Application of antimony as modifier is often unsatisfactory. In presented research antymony was applied in order to decrease surface tension of liquid alloy to minimize production of Al2O3 oxides on stream front and to maximize the castability of the alloy. Application antimony as a modifier of structure was assumed in the background. Reinforcement experimental castings were manufactured in variables technological conditions: range of pouring temperature 983-1013 K, temperature of mould 293-333 K and height of gating system 265 mm. The aim of researches of mechanical properties was investigated influence filler on compression strenght of composite shaped. Researches of compression strenght on composite samples, polymer concreate and aluminium skeleton samples were conducted. For samples of aluminium skeleton was obtained nonlinear dependence compresive stress on strain. This connected with buckling insignificant, which connectors of aluminium skeleton reinforcement were undergo during compression. Linear dependence compresive stress on strain for composite samples and polymer warp samples was observed. Polymer, sulfuric concrete samples under effect maximal stress undergo brittle cracking. However in case of samples from composite, aluminium skeleton limits brittle cracking of concrete. In composite samples obtained considerable increase of compression strenght in comparision with warp and reinforcement samples. The manufacturation conditions of experimental skeleton castings which ensure profitable mechanical properties of composite shaped. Based on tests, which were performed authors deduced, that manufacturing of composite castings is possible with use of traditional casting technology, without use of expensive laboratory - devices, with applied classical gating system. The following research will aimed to increase complexity of external and internal structure casting skeleton reinforcement.
14
Content available remote Analiza wybranych właściwości strukturalnych i wytrzymałościowych aluminiowych odlewów szkieletowych
Cholewa M., Dziuba-Kałuża M.
Archiwum Technologii Maszyn i Automatyzacji
|
2009
|
Vol. 29, nr 3
13-21
PL
W artykule przedstawiono geometrię przykładowego szkieletu i rdzenia opartą na osiemnasto-ścianie „hydraulicznym" oraz technologie wykonania rdzenia. Opracowano warunki technologiczne wytwarzania zamkniętych odlewów szkieletowych ze stopów AISi. Celem badań była analiza stopnia rozdrobnienia i jednorodności struktury odlewów szkieletowych oraz właściwości użytkowych tych odlewów. W związku z tym zmierzono odległości gałęzi drugorzędowych dendrytów (DAS) w charakterystycznych obszarach wykonanych odlewów. W badanych odlewach odległości wtórnych osi dendrytów DAS roztworu a osiągają najmniejsze wartości w obszarze stanowiącym geometryczne naroże ścian zewnętrznych zamykających odlew próbny, aczkolwiek są to wartości zbliżone do wartości we wszystkich charakterystycznych obszarach. Zbadano wytrzymałość na ściskanie próbek z odlewów szkieletowych. Największą wartość tej wytrzymałości uzyskano dla odlewu wykonanego przy parametrach technologicznych ujmujących temperaturę zalewania, temperaturę formy oraz wysokość układu wlewowego, a mianowicie: T/iń = 1013 K, T(ormy = 333 K, h = 265 mm. Opracowane warunki technologiczne umożliwiają wytworzenie odlewów o wymaganej zewnętrznej i wewnętrznej postaci geometrycznej i korzystnych właściwościach strukturalnych i wytrzymałościowych.
EN
In this paper geometry of skeleton casting and the core was shown together with its technology. Manufacturing parameters were determined for production of closed skeleton castings made of AISi alloys. The main aim was to analyze the refinement degree of the microstructure and its homogeneity together with operational properties of the castings. Dendrite arm spacing (DAS) was observed in characteristic regions of the casting. For studied castings the lowest values of DAS were observed in the corner of external walls of the casting. Nevertheless, values observed are close to those observed in other characteristic regions. To evaluate the mechanical properties compression test were performed. The highest compression strength was observed for skeleton casting manufactured under following technological conditions: pouring temperature 1013 K, mould temperature 333 K, height of the gating system 265 mm. Determined technological conditions enabled manufacturing of skeleton castings with desired external and internal geometry and favorable mechanical and structural properties.
15
Content available remote Analysis of structural properties of aluminium skeleton castings regarding the crystallization kinetics
Cholewa M., Dziuba-Kałuża M.
Archives of Materials Science and Engineering
|
2009
|
Vol. 38, nr 2
93-102
EN
Purpose: The aim of this research was the definition of technological parameters influence and modification treatment on structural properties of closed skeleton castings. Approach obtained maximal refinement of structure and minimal structure diversification. Design/methodology/approach: Skeleton castings were manufactured in acccordance to elaborated production technology. The subject of the research was the microstructural analysis of non - monolithic castings. Analisys of metallographic specimens and quantitative analysis of silicon crystals and secondary dentrite-arm spacing analysis of solution á were performed. Studies were executed for typical regions of skeleton castings. The regions were diversified regarding the cooling rate. Findings: Technological condictions and modification treatment were determined on advantageous structural properties (the great homogeneity and the greatest degree of fineness of microstructure). On basis of the reserach autors confirmed that in applied condictions of solidifiaction advantageous structur of AlSi11 alloy was obtained. Research limitations/implications: In the future autors will pursue to define influence of different modifiers (than antimony) on structural properties of skeleton castings. The modifiers are generally applied to refinement the structure of eutectic aluminium alloys. The aim of future resarch will be also to define optimum technological parameters which generate the best structural properties. Practical implications: This article shows method of structure design of AlSi11 alloys skeleton castings. This is essential with regard on usable properties of skeleton castings in future technical applications. Originality/value: Value of article is the elaborated manufacturing technology of skeleton castings and two methods of structure design of non – monolithic constructions with complicated geometry. The first method depended on elaborated parameters technological guidelines and advantageous technological condictions which enables to obtain the best structural properties. The second method depended on use of modifier which improve castability of AlSi11 alloys and enables to obtaine good filling of core channels of skeleton castings with more homogeneous structure.
16
Content available remote Studies of structural and mechanical properties of aluminum skeleton castings
Cholewa M., Dziuba-Kałuża M.
Archives of Foundry Engineering
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2009
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Vol. 9, iss. 3
29-34
EN
Skeleton castings were manufactured in accordance to elaborated production technology. The subject of the research was the microstructural analysis of non - monolithic castings. Analysis of metallographic specimens and quantitative analysis of silicon crystals and secondary dendrite-arm spacing analysis of solution \alfa were performed. Studies were executed for typical regions of skeleton castings. The regions were diversified regarding the cooling rate. The greatest value of compression strength were observed for casting manufactured according to technological conditions: pouring temperature Tpour 1013 K, temperature of the mould Tmould 333 K and height of the gating system h - 265 mm. Technological conditions and modification treatment were determined on base of advantageous structural properties (high homogeneity and refinement). On basis of the research authors confirmed that in applied conditions of solidification advantageous structure of AlSi11 alloy was obtained. The article showed the method of structure design of AlSi11 alloys skeleton castings, which was essential to obtain favorable operating properties of skeleton castings in future technical applications.
17
Content available remote Structural analysis of aluminum skeleton castings
Cholewa M., Dziuba-Kałuża M.
Archives of Foundry Engineering
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2008
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Vol. 8, iss. 3
29-36
EN
In this article authors showed method for manufacturing of skeleton castings with continuous external surface. Wall thickness of the external surface was 6 mm. The experimental casting was manufactured in order to verify the results of filling mould cavity which were obtained by numerical simulation. The aluminosilicate core was used to produce experimental aluminum skeleton castings with dimensions of (115x65x136) mm. Lower ingate with vertical getting system was used. On based on numerical simulations and preliminary experimental tests technological conditions were determined, which enables obtained castings on repeatable satisfactory geometry and requirement quality. Degree of refinement of structure in typical region of skeleton casting was compared. Qualitative and quantitative different degree of fineness of eutectic was confirmed. Selection of modification conditions AlSi alloy of skeleton casting is necessary. Based on tests, which were performed authors deduced, that manufacturing of skeleton castings is possible with use of traditional casting technology, without use of expensive laboratory – devices, with applied classical gating system and typical pouring temperature of Al alloys (ex. 740°C).
18
Content available remote Numerical simulation of pouring and solidification of closed skeleton casting
Cholewa M., Dziuba-Kałuża M.
Archives of Foundry Engineering
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2008
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Vol. 8, iss. 3s
9-12
EN
In this work authors showed results of simulation manufacturing closed skeleton casting. The aim of conducted simulations was the choice of thermal and geometrical parameters for the needs of designed calculations of the skeleton castings and the estimation of the guidelines for the technology of manufacturing. During simulation effect at mould filling process for the skeleton casting was analyzed. Analysis of temperature distribution and analysis of solidification closed aluminium skeleton casting were conduced. It was confirmed that the metal is flows at the external surfaces and fills internal channels of skeleton, until the moment of overall filling of the mould. Whole casting is solidification in finish of pouring mould. It is advantageous by reasons of satisfactory mould filling. Part of casting which was connected with feeder, on upper surface of casting solidified the slowest. in consequence to the lowest heat give up.
19
Content available remote Microstructure quantitative analysis of aluminum skeleton castings
Cholewa M., Dziuba-Kałuża M.
Archives of Foundry Engineering
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2008
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Vol. 8, iss. 4
241-250
EN
In this article authors showed method for manufacturing of closed skeleton castings with hypo - eutectic and eutectic aluminium alloys. Experimental castings were manufactured in variables technological conditions: range of pouring temperature 680÷740 °C, temperature of mould 20÷100 °C and height of gating system above casting level 105÷175 mm. Structural analysis of studied skeleton castings was conducted. Degree of refinement of structure in typical region of skeleton casting was compared. Qualitative and quantitative different degree of fineness of eutectic silicon was confirmed. Casting in established technological conditions enables manufactured skeletons which repeatable geometry, suitable external geometrical form of casting and required quality.
20
Content available remote Closed aluminium skeleton casting
Cholewa M., Dziuba-Kałuża M.
Archives of Foundry Engineering
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2008
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Vol. 8, iss. 1 spec.
53--56
EN
In this article authors showed method for manufacturing of skeleton castings with continuous external surface. Wall thickness of the external surface was 6 mm. The experimental casting was manufactured in order to verify the results of filling mould cavity which were obtained by numerical simulation. The aluminosilicate core was used to produce experimental aluminum skeleton castings with dimensions of (115x65x136) mm. Experimental casting was manufactured with elevated temperature of mould (370 K). Lower and stotted ingate with high geting system (300mm) was used. Analysis of ability of metal to fill the mould cavity in establish technological conditions was perfomed. Degree of refinement of structure in typicall region of skeleton casting was compared. Qualitative different degree of fineness of eutectic was confirmed. Selection of modification conditions AlSi alloy of skeleton casting is necessary. The manufacturing of skeleton casting in establish technological conditions enables obtained very good filling of mould cavity and suitable external geometrical form of casting.
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