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Numerical Simulation of Directional Solidification Process of Single Crystal Ni- Based Superalloy Casting

Szeliga D., Kubiak K., Sieniawski J.

Archives of Foundry Engineering

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2017

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Vol. 17, iss. 2

111--118

EN

The analysis of influence of mould withdrawal rate on the solidification process of CMSX-4 single crystal castings produced by Bridgman method was presented in this paper. The predicted values of temperature gradient, solidification and cooling rate, were determined at the longitudinal section of casting blade withdrawn at rate from 1 to 6mm/min using ProCAST software. It was found that the increase of withdrawal rate of ceramic mould results in the decrease of temperature gradient and the growth of cooling rate, along blade height. Based on results of solidification parameter G/R (temperature gradient/solidification rate), maximum withdrawal rate of ceramic mould (3.5 mm/min), which ensures lower susceptibility to formation process of new grain defects in single crystal, was established. It was proved that these defects can be formed in the bottom part of casting at withdrawal rate of 4 mm/min. The increase of withdrawal rate to 5 and 6 mm/min results in additional growth of susceptibility of defects formation along the whole height of airfoil.

2

Influence of chemical composition of nickel based superalloy on the formation of aluminide coatings

Zielińska M., Sieniawski J., Yavorska M.

Archives of Metallurgy and Materials

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2011

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Vol. 56, iss. 1

193-197

EN

The aim of the present work was to determine the influence of chemical composition of the nickel based superalloy on the thickness and microstructure of aluminide layer obtained in the CVD low activity process. For this purpose cylindrical samples were cut from the rods and castings made of commercially produced nickel superalloys: Inconel 713LC, Inconel 625, Inconel 738LC, Inconel 100, Inconel 718. The surface of the samples was ground up, degreased and cleaned. Than samples were placed in the retort and aluminized. The low activity process of aluminizing at the presence of AlCl3 and H2 was conducted. The cross -sections of aluminide coatings were investigated by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). There was established that a chemical composition of superalloy influences the microstructure and thickness of aluminide layer. Higher total concentration of superalloy elements such as Cr, Mo, W, Ti which segregate in the diffusion zone decrease the thickness of aluminide layer.

PL

Celem niniejszej pracy było określenie wpływu składu chemicznego nadstopów niklu na głębokość i mikrostrukturę warstwy aluminidkowej wytworzonej w niskoaktywnym procesie CVD. Do badań przyjęto pięć gatunków nadstopów niklu, najczęściej stosowanych do wytwarzania łopatek turbin silników lotniczych: Inconel 713LC, Inconel 625, Inconel 738LC, Inconel 100, Inconel 718. Z prętów i odlewów wycięto próbki walcowe, które następnie szlifowano, piaskowano i odtłuszczono. Następnie próbki umieszczono w retorcie i poddano procesowi aluminiowania. Niskoaktywny proces aluminiowania prowadzono w temperaturze 1050°C w obecności AlCl3 i H2. Badania mikrostruktury prowadzono na przekrojach poprzecznych uzyskanych warstw przy użyciu skaningowego mikroskopu elektronowego wyposażonego w detektor EDS. Stwierdzono, że skład chemiczny nadstopu wpływa na mikrostrukturę i głębokość wytworzonej warstwy. Większa sumaryczna zawartość składników stopowych tj. Cr, Mo, W, Ti, które segregują się w strefie dyfuzyjnej powoduje zmniejszenie głębokości warstwy aluminidkowej.

3

Criterion for selection the optimal physical and chemical properties of cobalt aluminate powder used in investment casting process

Zielińska M., Sieniawski J., Gajecka B.

Archives of Foundry Engineering

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2009

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Vol. 9, iss. 3

221-226

EN

The aim of this work was to determine physical and chemical properties of cobalt aluminate (CoAl2O4) modifiers produced by different companies and the influence of different types of modifiers on the grain size of high temperature creep resisting superalloys: Inconel 713C, René 77 and MAR-M 509. The first stage of the research work took over the investigations of physical and chemical properties of cobalt aluminate manufactured by three different companies: Remet, Mason Color and Permedia Lublin. There were determined the grain size distribution of cobalt aluminate powder, the average diameter and morphology of powder particles, phase composition, as well as sodium and cobalt content, pH value of water suspension and the bulk density. In the next step, the ceramic moulds were made with different kind of cobalt aluminate (Mason Color, Remet, Permedia Lublin) and its concentration (0, 5%) in the primary slurry. The samples of stepped shape were poured in the ceramic moulds prepared earlier. The average grain size of the \gamma phase was determined on the stepped samples. It was established that physical and chemical properties of cobalt aluminate modifier are different up to the manufacturer. For example the modifiers manufactured by Permedia; Mason Color and Remet companies have different the average diameter of particles- [...], and also cobalt content [...] mass, respectively. The grain size of \gamma matrix of superalloys depends on the kind of used inoculant. The best grain refinement of the matrix of superalloys: Inconel 713C, René 77 and MAR-M 509 was observed in the castings modified with the use of Mason Color modifier. On the grounds of literature data and obtained results it was established that the cobalt content of cobalt aluminate influences the intensity of nucleation process during the crystallization of superalloys: Inconel 713C, René 77 i MAR-M 509.