|Małgorzata Łągiewka, Zbigniew Konopka, Andrzej Zyska|
The article discusses the results of the studies of the effect of negative pressure in the mould and the casting system on the roughness of the casts’ surfaces. Roughness tests were performed on casts made of alloy EN AB 46000, by means of the pressure casting method in the Vertacast machine, and with the use of varying negative pressure in the mould. The surface roughness of the casts decreasing with a decrease in the pressure in the mould was determined based on the values of different characteristic surface roughness parameters. The cast roughness examinations were conducted on the Hommel Tester T1000 device.
Keywords: pressure casting, aluminium alloys, surface roughness,
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Grzegorz Gumienny, Barbara Kurowska
This study presents selected issues regarding the process of obtaining ausferrite from spheroidal cast iron without the application of thermal treatment to the casts. An ausferritic matrix, as well as strong mechanical properties, also ensures high abrasion and adhesion wear resistance. The proposed technology assumes that a change the chemical composition will take place, as a result of which it is possible to obtain an ausferritic matrix when the casts are cooled in the mould. Spheroidal graphite was obtained using Inmold technology. For the evaluation of the process of crystallization and transformation in the as-cast state, a thermal and derivational analysis (ATD) was carried out. Investigations of the effect of selected alloy additions in various proportions on the microstructure of the cast iron matrix were presented. It was demonstrated that it is possible to obtain ausferrite in spheroidal iron casts without the application of thermal treatment. The abrasion and adhesion wear resistance of cast iron was examined.
Keywords: spheroidal cast iron, ausferrite, ADI, thermal and derivational analysis (ATD), abrasion wear,
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Jagoda Ryba, Urszula Lelek-Borkowska, Agnieszka Tąta
The aim of the study was to improve the quality of 3D prints obtained by the FDM method (Fused Deposition Modeling) from ABS (acrylonitrile-butadiene-styrene), used for casting models. The agent used for smoothing the ABS was acetone.
The process of smoothing the surfaces of the printed model was carried out in an acetone chamber designed especially for this purpose. The casting models were exposed to acetone vapors at an elevated temperature. The process of smoothing the surface of the ABS prints made by the FDM method is crucial for the continued operation of the models, as a rough surface is an undesirable property, making it impossible to obtain smooth surfaces from the prepared casts. This generates costs connected with finishing treatment and the loss of some of the cast material.
Based on the results of the roughness tests performed on the examined models after exposure to acetone in the chamber, it was established that the best treatment method for ABS is to expose the print to acetone vapors at 56°C for 15 minutes. This procedure enables more accurate reconstruction of the casting model, which results in a lower material loss from the ready cast during the process of removing the material.
Keywords: FDM method, ABS, casting models, roughness, 3D print,
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Małgorzata Grudzień, Rafał Cygan, Zenon Pirowski, Łukasz Rakoczy
The main aim of this investigation was to determine the microstructural degradation of Inconel 713C superalloy during creep at high homologous temperature. The alloy in as cast condition was characterized by large microstructural heterogeneity. Inside equiaxed grains dendrite cores consisted of γ’ precipitates surrounded by channels of matrix, whereas enrichment of interdendritic spaces in carbide formers, Zr and B resulted in the formation of additional constituents, namely M3B2, Ni7Zr2 and eutectic island γ/γ’. Directional coarsening of γ′ precipitates (rafting) under applied stress and decomposition of primary MC-type carbides accompanied by the formation of secondary carbides enriched in Cr and γ’ phase was observed.
Keywords: degradation, Inconel 713C, NbC, M23C6,
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Artur Kudyba, Natalia Sobczak, Patrycja Turalska, Grzegorz Bruzda, Advenit Makaya, Laurent Pambaguian
The paper focuses on the experimental investigation of high temperature wetting behaviour of liquid pure Mg during a contact heating on Ni substrate by the sessile drop method. High temperature wettability test was performed by the classical sessile drop method at T = 700°C for t = 300 s, under flowing Ar 99.999% atmosphere, by using the equipment and testing procedures that have been developed by the Foundry Research Institute. In order to suppress effects of heating and cooling histories on wetting and spreading behaviours, Mg/Ni couple was introduced inside a metallic heater already preheated up to the test temperature, while after the wettability test, it was immediately removed to the cold part of the chamber. During the wettability test, images of the couple were recorded by high-resolution high-speed CCD camera. It was observed, that the wetting phenomenon (θ ≤ 90°) takes place immediately after melting of Mg sample. The Mg/Ni system shows a good wetting at T = 700°C after t = 300 s forming the final contact angle of 18°.
Keywords: sessile drop, wettability, reactivity, metal matrix composites (MMC),
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Tomasz Szymczak, Grzegorz Gumienny, Dorota Wilk-Kołodziejczyk, Tadeusz Pacyniak
The paper presents the results of studies of hypoeutectic silumin with a chromium addition used for pressure casting. A silumin with the composition similar to that of EN AC-46000 was used as the initial one. In order to introduce chromium into the initial silumin, an AlCr15 master alloy was applied. The amounts of the initial silumin and the AlCr15 master alloy were selected in the proportions making it possible to obtain about 0.1; 0.2; 0.3; 0.4 and 0.5 wt. % of Cr in the alloy. Both the initial silumin and the silumins with the chromium addition were examined. The results of the thermal and derivational analysis performed to investigate the silumins’ crystallization process have been presented. The microstructure of the silumins cast into an DTA tester and under pressure has been demonstrated. The basic mechanical properties of the pressure cast silumins have been presented. The results of the DTA analysis showed an effect of the chromium addition on the course of the crystallization process of the examined silumin. Three thermal effects are present on the silumin’s DTA curves, caused by the crystallization of the solid solution α(Al), and of two eutectics α + Al15(Fe,Mn)3Si2 + β and α + Al2Cu + AlSiCuFeMnMgNi + β. The introduction of chromium in the amount of about 0.2 wt. % caused the presence of an additional thermal effect on the derivation curve, originating from the crystallization of the intermetallic phase containing chromium. The crystallization of this phase occurs before the precipitation of the dendrites of phase α(Al) from the liquid. The microstructure analysis of the silumins cast into the DTA tester showed the presence of precipitations of a "new" phase in the silumins containing 0.2% wt. Cr or more. With the occurrence of an additional thermal effect on the DTA curves as well as the "new" phase in the silumin’s microstructure, the lack of phase Al15(Fe,Mn)3Si2 was observed. In the pressure cast silumins, the chromium addition also caused the formation of a "new" intermetallic phase, which occurs with the Cr content of about 0.3 wt. % or more. Its morphology is similar to a faceted one. With an increase of the chromium content, the size of this phase significantly increases as well. The investigations of the basic mechanical properties of the pressure cast silumins showed that the Cr addition makes it possible to significantly increase mainly the tensile strength Rm and the unit elongation A. To a lesser extent, this element caused an increase of the hardness HB. The values of the proof stress Rp0.2 of the initial silumin and the silumins with an increased chromium content do not change significantly. The highest mechanical properties were obtained for the silumins containing about 0.2 and 0.3 wt. % Cr.
Keywords: silumin, chromium, microstructure, mechanical properties, high pressure die casting,
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