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PL
W artykule przedstawiono wyniki badań odporności na korozję wżerową napoin z nadstopu niklu Alloy 59 w syntetycznym roztworze, symulującym środowisko pracy charakterystyczne dla skruberów FGD. Wykonano testy laboratoryjne, które polegały na umieszczeniu próbki w roztworze o zadanej temperaturze na 24 godziny. Przyjęto temperaturę początkową 90 °C, a następnie zwiększano o 5 °C w kolejnym badaniu, aż do pojawienia się wżerów korozyjnych. Za miarę odporności na korozję wżerową przyjęto obecność w materiale ubytków korozyjnych oraz zmiany masy. Na podstawie wyników przeprowadzonych badań wyznaczono krytyczną temperaturę korozji wżerowej (CPT – ang. Critical Pitting Temperature) napoin na poziomie 100 °C.
EN
This article presents the results of pitting corrosion resistance tests of padding welds made of nickel superalloy Alloy 59 in a Green Death solution, which simulate FGD scrubber environment. In the laboratory tests the specimens were placed in the solution at a given temperature per 24 hours. The initial temperature was set at 90 °C and then increased by 5 °C in the next test, until corrosion pits appeared. A visual examination of specimens surfaces, along with mass loses were performed to characterize the pitting resistance of material. On the basis of the results, the critical pitting temperature (CPT) of padding welds at a level of 100 °C was determined.
PL
W niniejszej pracy przeprowadzono charakterystykę składników mikrostrukturalnych w nadstopie na osnowie niklu oraz ich rolę w kontekście wrażliwości wybranego nadstopu do pęknięć likwacyjnych po spawaniu łukowym elektrodą nietopliwą. Materiał dostarczony w postaci odlewu charakteryzował się znaczną niejednorodnością, związaną z różną zawartością pierwiastków w rdzeniach dendrytów i w przestrzeniach międzydendrytycznych. W trakcie obserwacji za pomocą skaningowej mikroskopii elektronowej zaobserowano stosunkowo duży udział wydzieleń fazy międzymetalicznej γ’ w rdzeniach dendrytów. W przestrzeniach międzydendrytycznych, w wyniku segregacji pierwiastków stopowych, w trakcie krzepnięcia odlewu wydzieliły się wyspy eutektyczne γ/γ’, jak również węgliki bogate w pierwiastki trudnotopliwe, mianowicie Hf i Ta. Ciepło wprowadzone do materiału w trakcie spawania doprowadziło w strefie wpływu ciepła do częściowego rozpuszczenia wydzieleń fazy γ’ w osnowie γ. Tworząca się w wysokiej temperaturze cienka nierównowagowa warstewka cieczy zaobserwowana lokalnie wzdłuż granic dendrytów była czynnikiem sprzyjającym do zainicjowania pęknięć i ich rozprzestrzeniania się w trakcie chłodzenia. Na podstawie przeprowadzonej analizy stwierdzono, że ciecz pojawiała się w wyniku nierównowagowego nadtapiania głównie wydzieleń fazy międzymetalicznej γ’.
EN
In the present study, the characterization of microstructural constituents in the Ni-based superalloy was carried out, as well as their role in the susceptibility to liquation cracking in heat affected zone during tungsten inert gas. The casting was characterized by considerable heterogeneity in the dendrite cores and interdendritic spaces. During scanning electron microscopy investigation significant volume fraction of cubic- and spherical-shaped precipitates of γ’ phase in dendrite cores was observed. In interdendritic spaces, as a result of the segregation of alloying elements during the solidification of the casting, eutectic γ/γ’ islands and carbides rich in refractory elements, namely Hf and Ta were also present. In the heat affected zone, heat input induced by welding led to partially dissolving of the γ’ precipitates in the surrounding γ matrix channels. A thin non-equilibrium liquid film that a appeared locally along the grain boundaries in the HAZ was a key factor in the initiation of cracks and their spreading during cooling. Based on the observation, it was found that the liquid phase appeared as a result of constitutional liquation.
3
Content available remote Skłonność do pękania gorącego złączy spawanych z nadstopu niklu Inconel 617
PL
W pracy przedstawiono wyniki oceny skłonności do pękania gorącego nadstopu niklu Inconel 617. Badania przeprowadzono na blachach o grubości 1, 3 oraz 5 mm wykorzystując próbę Houldcrofta w warunkach zmiennej sztywności złącza. W próbie Houldcrofta, używając nietopliwej elektrody w osłonie gazów obojętnych, wykonano przetopienia stopu Inconel 617 z materiałem dodatkowym i bez materiału dodatkowego. W próbie wyznaczono wskaźnik A rozumiany jako stosunek długości pęknięcia do długości próbki, który jest wyrażany w procentach. Badania zostały uzupełnione o analizę metalograficzną i fraktograficzną, mikroanalizę składu chemicznego EDS z powierzchni pęknięcia oraz powierzchni prostopadłej do kierunku spawania. Uzyskane wyniki pozwoliły na opisanie mechanizmu pękania złączy spawanych z nadstopu niklu Inconel 617.
EN
The paper presents the results of the propensity of hot cracking of the nickel superalloy Inconel 617. The tests were carried out on nickel sheets with a thickness of 1, 3 and 5 mm using a Houldcroft’s test in variable stiffness of the welded joint. In Houldcroft’s test by using tungsten electrode in inert gas, remelting alloy Inconel 617 with additional material without additional material were made. In test the indicator A was designated, understood as the ratio of the crack length to the length of the sample, which is expressed as a percentage. Studies have been complemented by metallographic and fractography analysis, also made microanalysis of the chemical composition EDS of the crack surface and the surface, which is perpendicular to the direction of welding. The results allowed to describe the hot cracking mechanism of welded joints of nickel superalloy Inconel 617.
4
PL
Odlewy precyzyjne ze stopu Inconel 713C znalazły zastosowanie na elementy silników lotniczych pracujących w wysokich temperaturach oraz w agresywnym środowisku spalin. Praktyka przemysłowa wykazała, że w procesie odlewnia precyzyjnego, tak skomplikowanych elementów, pojawiają się wady odlewnicze w postaci rzadzizn, porowatości oraz pęknięć. Powoduje to konieczność opracowania technologii naprawy tego typu odlewów. W pracy przedstawiono wyniki badań metalograficznych napoin na nadstopie niklu Inconel 713C, wykonanych laserem oraz za pomocą napawania plazmowego. Proces napawania prowadzono na modelowych płytach próbnych, w celu określenia problemów technologicznych i materiałowych związanych ze spawalnością stopu Inconel 713C. Badania obejmowały analizę makro i mikrostruktury napoiny, materiału rodzimego i strefy wpływu ciepła. Wyniki badań strukturalnych obszarów napoin wskazują, że stop Inconel 713C należy zaliczyć do materiałów trudno spawalnych. W napoinach wykonanych laserowo ujawniono pęknięcia materiału głównie w strefie wpływu ciepła oraz na linii wtopienia, gdzie na nadtopionych ziarnach krystalizują kryształy napoiny. Tego typu pęknięć nie obserwowano w napoinach wykonanych plazmowo. Stwierdzono, ze względu na możliwość ręcznego napawania oraz brak niezgodności spawalniczych, technologią o większym potencjale zastosowania jest napawanie plazmowe.
EN
Inconel 713C precision castings are used as aircraft engine components exposed to high temperatures and the aggressive exhaust gas environment. Industrial experience has shown that precision-cast components of such complexity contain casting defects like microshrinkage, porosity, and cracks. This necessitates the development of repair technologies for castings of this type. This paper presents the results of metallographic examinations of pad welds on the Inconel 713C nickel-based superalloy, made by laser and by plasma-arc pad welding. The pad welding process was carried out on model test panels in order to determine the technological and material-related problems connected with the weldability of the Inconel 713C alloy. The studies included analyses of the macro and microstructure of the pad welds, the base materials, and the heat-affected zones. The results of the structural analyses of the pad welds indicate that Inconel 713C should be classified as a low-weldability material. In the pad welds made by laser, cracks were identified mainly in the heat-affected zone and at the melted zone interface, where pad weld crystals formed on partially-melted grains. Cracks of this type were not identified in the pad welds made using the plasma-arc method. It has been concluded that due to the possibility of manual pad welding and the absence of welding imperfections, the technology having the greater potential for application is plasma-arc pad welding.
5
EN
Blades and vanes structural components of turbine engines are processed to withstand high temperature during loading conditions of service, fulfilling high standards of quality control and safety for effective use. Therefore, characterization of mechanical properties, such as creep behaviour, are necessary for appropriate control procedures on prediction of exploitation lifetime. The materials mostly used in manufacturing of these components are single crystal nickel-base superalloys. Creep behaviour characterization, composed of creep-rupture tests, were performed on a single crystal rods made of CMSX–4 superalloy obtained at a withdrawal rate of 3 and 5 mm/min. Cylindrical rods were directly solidified in the [001] direction in an ALD Vacuum Technologies investment casting furnace (VIM-IC 2). Then, prepared specimens were tested in tensile creep under constant stress of 248 MPa at a temperature of 982°C. The longitudinal and cross sections from tested samples, were characterized by TEM and X-ray diffraction methods. It was found that all samples showed a similar rupture mechanism. The electron backscatter diffraction (EBSD) measurements showed that octahedral and cubic slip systems were present however, the critical stress was present on {111} planes. It was observed that the cubic slip has the highest calculated Schmid factor along the dendrite cores while the octahedral slip occurs through entire sample volume. Samples obtained at 5 mm/min possess a visible widening of coherent scattering regions as shown in inverse pole figures. The reason of these changes is the fact that higher rate has the greatest probability of creating small angle boundaries, often occurring in the interdendritic channels.
PL
Monokrystaliczne odlewy nadstopu niklu CMSX–4 stosuje się na najbardziej wytężone elementy silnika odrzutowego, takie jak łopatki turbiny wysokiego ciśnienia. Musza one charakteryzować się dużą żarowytrzymałością oraz żaroodpornością. Dlatego jest ważne precyzyjne określenie wpływu zjawiska pełzania na strukturę tego materiału w zależności od warunków jego wytwarzania. Celem pracy było scharakteryzowanie zmian strukturalnych oraz określenie wytrzymałości na pełzanie monokrystalicznych odlewów otrzymanych z prędkościami wyciągania formy wynoszącymi 3 oraz 5 mm/min.
EN
The paper presents results of calorimetric studies of foundry nickel superalloys: IN100, IN713C, Mar-M247 and ŻS6U. Particular attention was paid to determination of phase transitions temperatures during heating and cooling. The samples were heated to a temperature of 1500°C with a rate of 10°C min–1 and then held at this temperature for 5 min. After a complete melting, the samples were cooled with the same rate. Argon with a purity of 99.99% constituted the protective atmosphere. The sample was placed in an alundum crucible with a capacity of 0.45 cm3. Temperature and heat calibration was carried out based on the melting point of high-purity Ni. The tests were carried out by the differential scanning calorimetry (DSC) using a Multi HTC high-temperature calorimeter from Setaram. Based on the DSC curves, the following temperatures were determined: solidus and liquidus, dissolution and precipitation of the γ’ phase, MC carbides and melting of the γ’/γ eutectic. In the temperature range of 100-1100°C, specific heat capacity of the investigated superalloys was determined. It was found that the IN713C and IN100 alloys exhibit a higher specific heat while compared to the Mar-M247 and ŻS6U alloys.
PL
W artykule przedstawiono wyniki badań w zakresie identyfikacji i lokalizacji pęknięcia warstwy aluminidkowej na stopie niklu, pod wpływem obciążeń zmęczeniowych, z zastosowaniem nieniszczących technik badawczych. Testom zmęczeniowym poddano próbki ze stopu niklu z warstwą aluminidową o grubości ok. 20 i 40 μm uzyskaną w procesie chemicznego osadzania z fazy gazowej CVD (Chemical. Vapor. Deposition). Do identyfikacji uszkodzenia zdefiniowanego jako pęknięcie warstwy wykorzystano metodę prądów wirowych (ET) oraz optyczną metodę elektronicznej interferometrii plamkowej (ESPI). Ta ostatnia metoda pozwoliła na wykrycie pęknięć tworzących się w czasie cyklicznego obciążenia próbki, w oparciu o wskazanie lokalizacji deformacji. Umożliwiło to ocenę trwałości zmęczeniowej warstwy, której pękanie poprzedza uszkodzenie całej próbki.
EN
The paper presents results of fatigue test conducted on nickel based superalloy MAR 247 with aluminide layer of varying thickness. The trial for identification of damage localization with the use of Eddy Current (ET) and Electronic Speckle Pattern Interferometry optical method (ESPI) was made. It allowed for detection of cracks forming during cyclic loading of the sample. This enabled evaluation of fatigue life of the layer, as the formation of crack precede sample decohesion. Based on the fatigue tests created Wöhler curves were assigned for the samples with the aluminide layer of 20 and 40 microns thickness.
EN
Paper presents the assessment of impact of heat treatment on durability in low-cycle fatigue conditions (under constant load) in castings made using post-production scrap of MAR-247 and IN-713C superalloys. Castings were obtained using modification and filtration methods. Additionally, casting made of MAR-247 were subjected to heat treatment consisting of solution treatment and subsequent aging. During low-cycle fatigue test the cyclic creep process were observed. It was demonstrated that the fine-grained samples have significantly higher durability in test conditions and , at the same time, lower values of plastic deformation to rupture Δ□pl. It has been also proven that durability of fine-grained MAR-247 samples can be further raised by about 60% using aforementioned heat treatment.
EN
The results of structure observations of Ni base superalloy subjected to long-term influence of high pressure hydrogen atmosphere at 750K and 850K are presented. The structure investigation were carried out using conventional light-, scanning- (SEM) and transmission electron microscopy (TEM). The results presented here are supplementary to the mechanical studies given in part I of this investigations. The results of study concerning mechanical properties degradation and structure observations show that the differences in mechanical properties of alloy subjected different temperature are caused by more advanced processes of structure degradation during long-term aging at 850K, compare to that at 750K. Higher service temperature leads to formation of large precipitates of δ phase. The nucleation and growth of needle- and/or plate-like, relative large delta precipitates proceed probably at expense strengthening γ" phases. Moreover, it can't be excluded that the least stable γ" phase is replaced with more stable γ' precipitates. TEM observations have disclosed differences in dislocation structure of alloy aged at 750K and 850K. The dislocation observed in alloy subjected to 750K are were seldom observed only, while in that serviced at high stress and 850K dislocation array and dislocation cell structure was typical.
EN
As the costs of structural materials are increasing, manufacturers reach to produce not only energy efficient but powerful engines to meet customer demand. Economics dictate a need of researching into new techniques of using older superalloy designs to achieve superior performance. This paper showcases a thermo-mechanical fatigue reliability comparison between well, established superalloys: IN-738LC and CM-247LC in either cast or directionally solidified form.
11
Content available Kinetics of Grain Growth in 718 Ni-Base Superalloy
EN
The Haynes® 718 Ni-base superalloy has been investigated by use of modern material characterization, metallographic and heat treatment equipment. Grain growth annealing experiments at temperatures in the range of 1050 – 1200 oC (1323–1473K) for time durations in the range of 20 min-22h have been conducted. The kinetic equations and an Arrhenius-type equation have been applied to compute the grain-growth exponent n and the activation energy for grain growth, Qg, for the investigated alloy. The grain growth exponent, n, was computed to be in the range of 0.066-0.206; and the n values have been critically discussed in relation to the literature. The activation energy for grain growth, Qg, for the investigated alloy has been computed to be around 440 kJ/mol; and the Qg, data for the investigated alloy has been compared with other metals and alloys and ceramics; and critically analyzed in relation to our results.
PL
Nadstop na bazie niklu Haynes ® 718 badano przy użyciu nowoczesnych urządzeń do charakterystyki materiałów, metalografii i obróbki cieplnej. Przeprowadzono badania wzrostu ziarna podczas wyżarzania w zakresie temperatur 1050 - 1200 ° C (1323-1473K) w czasie trwania od 20 minut do 22 godzin. Równania kinetyczne i równanie typu Arrheniusa zostały zastosowane do obliczania wykładnika wzrostu ziarna n oraz energii aktywacji wzrostu ziarna, Qg, dla badanego stopu. Obliczona wartość wykładnika wzrostu ziarna, n, mieści się w zakresie od 0.066 do 0.206 i została krytycznie przedyskutowana w odniesieniu do literatury. Obliczona energia aktywacji wzrostu ziaren, Qg, wynosi dla badanego stopu na około 440 kJ / mol. Dane Qg dla badanego stopu porównywano z danymi dla innych metali, stopów i ceramiki oraz krytycznie analizowano w odniesieniu do naszych wyników.
EN
Paper presents the results of evaluation of heat resistance and specific heat capacity of MAR-M-200, MAR-M-247 and Rene 80 nickel superalloys. Heat resistance was evaluated using cyclic method. Every cycle included heating in 1100°C for 23 hours and cooling for 1hour in air. Microstructure of the scale was observed using electron microscope. Specific heat capacity was measured using DSC calorimeter. It was found that under conditions of cyclically changing temperature alloy MAR-M-247 exhibits highest heat resistance. Formed oxide scale is heterophasic mixture of alloying elements, under which an internal oxidation zone was present. MAR-M-200 alloy has higher specific heat capacity compared to MAR-M-247. For tested alloys in the temperature range from 550°C to 800°C precipitation processes (γ′, γ′′) are probably occurring, resulting in a sudden increase in the observed heat capacity.
PL
W pracy przedstawiono analizę wyników pomiarów i symulacji numerycznej rozkładu wartości temperatury W monokiystalicznym odlewie pręta z nadstopu niklu CMSX-4 wytwarzanego metodą Bridgmana. Opracowano model geometryczny zestawu modelowego i przestrzennego otoczenia formy ceramicznej oraz przyjęto warunki brzegowe. Ustalono wpływ kształtu modelu geometrycznego i zadanych warunków brzegowych na wyniki symulacji numerycznej procesu krystalizacji monokrystalicznego odlewu w danych warunkach technologicznych. Wykonano symulację numeryczną procesu krystalizacji kierunkowej oraz ustalono rozkład wartości temperatury w odlewie, formie ceramicznej, płycie izolacji cieplnej oraz przegrodzie cieplnej z zastosowaniem programu ProCAST. Określono wpływ wartości współczynników: wymiany ciepła na styku dwóch materiałów, emisyjności formy ceramicznej, a także właściwości cieplnych i fizycznych stopu CMSX-4 na rozkład wartości temperatury w odlewie. Przeprowadzono weryfikację doświadczalną przyjętych warunków brzegowych i wartości współczynników cieplnych i fizycznych materiałów odlewu i formy ceramicznej. Stwierdzono, że największy wpływ na prognozowany rozkład wartości temperatury w odlewie mają wartości współczynnika wymiany ciepła na styku powierzchni odlewu i formy ceramicznej oraz współczynniki cieplne i fizyczne materiału odlewu i formy.
EN
The authors conducted analysis of the measurement results and performed a numerical simulation of the temperature distribution in a single crystal cast rod made of the CMSX-4 nickel superalloy, which was manufactured by the Bridgman method. The geometric model of the model set and of the ceramic shell mold surrounding it were developed (Fig. 3) and the boundary conditions were selected (Fig. 4+6) (Tab. 1, 2). The infiuence of the shape of the geometric model and the boundary conditions on the numerical simulation results of the solidification process of a single crystal cast under given technological conditions was determined. The numerical simulation of the directional solidification process was performed and the temperature distribution in the cast, the ceramic shell mold, the thermal insulating plate and the thermal baffie was determined using the ProCAST program (Fig. 11). The infiuence of the emissivity coefficient of the ceramic shell mold, the heat transfer coefficient on the contact surface of the two materials as well as the infiuence of the thermal and physical properties of the CMSX-4 superalloy on the temperature distribution in the cast were determined (Fig. 7+10). The authors conducted experimental verification of the selected boundary conditions as well as the thermal and physical coefficients values for the cast material and the material of the ceramic shell mold. It has been proved that the value of the heat transfer coefficient on the contact surface of the cast and the ceramic shell mold as well as the thermal and physical coefficients values have the greatest infiuence on the temperature distribution in the cast.
EN
This paper provides an analysis of experimental research and results of investment casting process. Temperature field in a ceramic mold is one of the problems during numerical simulation. Reducing the costs of production in precision casting involves the reduction of scraps, which is one of the fundamental problems of the foundry industry. Reducing these costs is associated with optimization of precision casting technology of aircraft engines critical parts, including control of the solidification front in thin-walled castings of nickel super alloys cast in a vacuum. It is achieved by changing the geometrical characteristics of the ceramic mold. The results of the tests were used to optimize the industrial production of aircraft components in Precision Foundry of WSK Rzeszów. Temperature distribution gained in the conducted tests allowed verification and optimization of computer simulations.
PL
Celem pracy było opracowanie warunków procesu nisko i wysokoaktywnego aluminiowania nadstopu niklu René77 z zastosowaniem metody chemicznego osadzania z fazy gazowej. Wytworzono dyfuzyjne warstwy żaroodporne na osnowie aluminidków niklu. Określono wpływ czasu procesu prowadzonego w temperaturze 1050°C na głębokość wytworzonych warstw. Celem zwiększenia grubości warstwy ochronnej zastosowano dodatkowe wyżarzanie po procesie wysokoaktywnym. Wykonano badania odporności na utlenianie wytworzonych warstw oraz analizę składu fazowego warstwy. Stwierdzono, że wytworzone warstwy aluminidkowe zwiększają odporność na utlenianie podłoża – stopu René 77.
EN
The aim of the study was development of aluminizing process of the René 77 superalloy by the CVD method. Heat resistant diffusion layers based on nickel aluminides were produced. The influence of time of CVD process carried out at 1050°C on the thickness of the coatings was determined. Additional annealing was also applied after high activity process to increase the thickness of the protective coating. Phase composition of the aluminide coatings was examined. On the basis of the oxidation tests results it was found that applied coatings improved oxidation resistance of René 77 superalloy.
EN
The paper presents the results of studies to determine the effect of complex surface and bulk modification and double filtration during mould pouring on the stereological parameters of macrostructure and mechanical properties of castings made from the post-production waste IN-713C and the MAR-247 nickel alloys. The evaluation covered the number of grains per 1mm2 of the sample surface area, the average area of grains and the shape index, hardness HB, tensile strength and resistance to high temperature creep. The results indicate the possibility of controlling the stereological parameters of macrostructure through application of several variants of the modification, controlling in this way also different low- and high-temperature properties. The positive effect of double filtration of the alloy during mould pouring on the metallurgical quality and mechanical properties of castings has also been emphasized.
EN
Impact of surface and volume modification and double filtration during pouring the moulds on basic mechanical properties and creep resistance of nickel superalloys IN-713C and MAR-247 in conditions of accelerated creep of castings made of post-production scrap of these alloys is evaluated in this paper. The conditions of initiation and propagation of cracks in the specimens were analysed with consideration of stereological properties of material macro- and microstructure. It has been proven that in the conditions of high-temperature creep at 980 C and at stress [...] = 150 MPa, creep resistance of superalloy MAR-247 is more than 10 times higher than the creep resistance of IN-713C alloy. In case of IN-713C alloy, the creep resistance negligibly depends on macrograin sizes. But, the macrograin size considerably affects the time to failure of specimens made of alloy MAR-247. Creep resistance of specimens made of coarse grain material was 20% higher than the resistance of fine grain materials.
EN
The paper presents the results of evaluation of the metallurgical quality of master heat ingots and of the identification of non-metallic inclusions (oxides of Al., Zr, Hf, Cr, etc.), which have been found in the shrinkage cavities formed in these ingots. The inclusions penetrate into the liquid alloy, and on pouring of mould are transferred to the casting, especially when the filtering system is not sufficiently effective. The specific nature of the melting process of nickel and cobalt alloys, carried out in vacuum induction furnaces, excludes the possibility of alloy refining and slag removal from the melt surface. Therefore, to improve the quality of castings (parts of aircraft engines), it is so important to evaluate the quality of ingots before charging them into the crucible of an induction furnace. It has been proved that one of the methods for rapid quality evaluation is an ATD analysis of the sample solidification process, where samples are taken from different areas of the master heat ingot. The evaluation is based on a set of parameters plotted on the graph of the dT/dt derivative curve during the last stage of the solidification process in a range from TEut to Tsol.
19
Content available remote Interactions at the mould - modifying coating - molten nickel alloy interface
EN
The study describes thermal-chemical interactions that take place in the molten nickel alloy-ceramic mould system, where the mould is either coated with a modifying coating ('blue' mould) or is not ('white' mould). The ceramic mould based on zirconium silicate was made by investment process at the WSK Rzeszów Foundry. The main component of the modifying coating was cobalt aluminate CoAl2O4 added in an amount of 10%. Thermodynamic calculations indicated the possibility of chemical reactions taking place between the chemically active nickel alloy constituents (Al, Ti, Hf, Ta and Nb) and the components of a ceramic mould and modifying coating. The result of such interactions is the risk of the formation of cracks on the surface of mould and molten metal penetration into these cracks, combined with the formation of casting defects, like burns-on, pitting, etc., as proved by extensive X-ray microanalysis. Changes of chemical composition in the surface layer of castings were also reported.
EN
The work includes studies to determine the significance of the effect of selected technological parameters of moulding and casting conditions on the macrostructure of IN-713C cast nickel alloy. Two-level, fractional 24-1 experiment was carried out, requiring eight experiments. The evaluation covered the number of grains per 1mm2 of the sample surface, the average grain surface area, and the shape index. Macrostructure of test castings indicates a positive effect of combined surface and bulk inoculation treatment, with the effect of surface inoculation prevailing as regards its importance. Statistically significant effect on the number and surface of grains have in descending order: surface modification, bulk modification and temperature of alloy pouring.
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