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Investment casting parameters impact on IN 713C nickel-based superalloy microstructure DOI:


  The basic process for manufacturing of aircraft engine hot section elements made of nickel-based superalloys is investment casting using multilayer ceramic shell moulds. Introduction of new engines designs with higher thrust, lower fuel consumption and lower noise emissions enforce continual modification of casting materials, models, ceramic moulds, including melting, pouring and heat treatment processes parameters. The aim of this study was to determine the effect of pouring temperature and cobalt aluminate modifier in the subsurface layer of the mould on macrostructure of the IN 713C castings. The size of misruns, chill, columnar and equiaxed zones on the surface of the wedge castings is most affected by pouring temperature. Additionally it was proved that cobalt aluminate is an effective modifier of the IN713C superalloy causing not only refinement of equiaxed grains, but also reduction in the columnar grain size fraction. Key words: investment casting, superalloys, microstructure, grain size, dendrite arm spacing.1. INTRODUCTION IN 713C superalloy in as-cast state is mainly used, among others, for aircraft engine components. These elements are casted using the lost-wax method with multilayer ceramic moulds. Casted gas turbine blades are characterised by coarse grains of heterogeneous microstructure. The casting often does not meet mechanical properties required from the kinds of elements used in the aerospace industry [1, 2]. The microstructure improvement of nickel-based superalloy blades may be obtained by appropriate shaping of grains size during the casting process [3, 4]. Controlled grain size can be achieved by specific pouring temperature, mould temperature, and the use of modifier in the surface layer of the mould [5, 6]. Highest grain refinement of nickel-based superalloys was obtained with application of cobalt aluminate modifier [7, 8]. The aim of presented study was to determine the effect of pouring temperature and Co[...]

Wpływ parametrów technologicznych odlewania na strukturę odlewów precyzyjnych z nadstopu niklu IN 713C DOI:10.15199/28.2016.2.2

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1. CEL PRACY Nadstop niklu IN 713C jest stosowany między innymi na łopatki turbin silników lotniczych, odlewane precyzyjnie metodą traconego wosku w wielowarstwowych formach ceramicznych. Łopatki turbin często charakteryzują się gruboziarnistą i niejednorodną strukturą, która nie spełnia rygorystycznych wymagań dotyczących części wykorzystywanych w przemyśle lotniczym. Poprawę struktury łopatek wytworzonych z nadstopów niklu można uzyskać w wyniku odpowiedniego kształtowania wielkości ziarna w procesie odlewania. Ziarna o kontrolowanych rozmiarach można otrzymać dzięki odpowiedniej temperaturze zalewania, temperaturze formy i zastosowaniu modyfikatora w powierzchniowej [...]

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