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1

Influence of Rare Earth Sm Addition on Microstructure and Tensile Properties of Al-Si-Cu 319 Alloy

Patel D. N., Sutaria Mayur P.

Archives of Foundry Engineering

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2023

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Vol. 23, iss. 1

25--33

EN

In the present investigation, the influence of addition of the rare earth element samarium (Sm) in different concentrations (0, 0.1, 0.3, 0.5, 0.7 and 0.9wt.%) on the microstructure and tensile properties of the Al-Si-Cu 319 alloy have been evaluated. Microstructural constituents such as SDAS of α-Al and characteristics of eutectic silicon particles were observed by optical microscopy. It was concluded from the findings that Sm addition reduces the size of secondary dendrite arm spacings (SDAS) and altered the morphology of the eutectic silicon particles from needle-like to lamellar and smaller segments. The tensile properties of the Al-Si-Cu 319 alloy improved with the concentration of Sm. It was found that the highest tensile properties were obtained at 0.7wt.% addition of Sm, i.e., 55.5% higher than unmodified 319 alloy. With the further addition of the Sm above 0.7wt.%, it does not improve the tensile properties of the alloy. This can be attributed to the precipitation of the brittle and needle like quaternary Sm-rich intermetallic compounds observed through Scanning electron microscopy.

2

Effect of Maximum Piston Velocity on Internal Homogeneity of AlSi9Cu3(Fe) Alloy Processed by High-Pressure Die Casting

Matejka Marek, Bolibruchowá Dana, Podprocká R.

Archives of Foundry Engineering

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2022

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Vol. 22, iss. 4

34--40

EN

High-pressure die casting results in a high quality surface and good mechanical properties of castings. Under the effect of pressure, integral and solid castings are achieved without a large number of foundry defects. The correct and proper setting of technological parameters plays a very important role in minimizing casting defects. The aim of the presented article is to determine the optimum maximum piston velocity for a casting in the high-pressure casting process with two height variants, depending on their internal quality. It is because the internal quality of particular castings is important in terms of proper functionality in operations where the biggest problem is the porosity of the casting. The main cause of porosity formation is the decreasing solubility of gases (most often hydrogen) during the melt solidification. Solubility represents the maximum amount of gas that can dissolve in a metal under equilibrium conditions of temperature and pressure. Macroporosity and microporosity were determined from the sections of the surfaces in the determined zones of the castings. Here, the results was that the macroporosity decreased with increasing piston velocity. Ideal microstructure was evaluated at a piston velocity of 3 m/s for both types of castings. On the other hand, the increase in tube size has shown that velocities of 3 m/s and higher, the tube is more prone to macroporosity formation. The highest hardness was achieved at the piston velocity of 2 m/s at both tube lengths.

3

A Study of Microstructure and Porosity Formation in High-Pressure Die-Casting

Matejka Marek, Bolibruchová D., Podprocká R.

Archives of Foundry Engineering

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2021

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Vol. 21, iss. 4

127--130

EN

The technology of high-pressure die-casting (HPDC) of aluminum alloys is one of the most used and most economical technology for mass production of castings. High-pressure die-casting technology is characterized by the production of complex, thin-walled and dimensionally accurate castings. An important role is placed on the effective reduction of costs in the production process, wherein the combination with the technology of high-pressure die-casting is the possibility of recycling using returnable material. The experimental part of the paper focuses on the analysis of a gradual increase of the returnable material amount in combination with a commercial purity alloy for the production of high-pressure die-castings. The returnable material consisted of the so-called foundry waste (defective castings, venting and gating systems, etc.). The first step of the experimental castings evaluation consisted of numerical simulations, performed to determine the points of the casting, where porosity occurs. In the next step, the evaluation of areal porosity and microstructural analysis was performed on experimental castings with different amounts of returnable material in the batch. The evaluation of the area porosity showed only a small effect of the increased amount of the returnable material in the batch, where the worst results were obtained by the casting of the alloy with 90% but also with 55% of the returnable material in the batch. The microstructure analysis showed that the increase in returnable material in the batch was visibly manifested only by a change in the morphology of the eutectic Si.

4

Effect of Remelting on Microstructure of the AlSi9Cu3 Alloy with Higher Iron Content

Matejka M., Bolibruchova D.

Archives of Foundry Engineering

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2018

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Vol. 18, iss. 4

25--30

EN

Secondary or multiple remelted alloys are common materials used in foundries. For secondary (recycled) Al-Si-Cu alloys, the major problem is the increased iron presence. Iron is the most common impurity and with presence of other elements in alloy creates the intermetallic compounds, which may negatively affect the structure. The paper deals with effect of multiple remelting on the microstructure of the AlS9iCu3 alloy with increased iron content to about 1.4 wt. %. The evaluation of the microstructure is focused on the morphology of iron-base intermetallic phases in caste state, after the heat treatment (T5) and after natural aging. The occurrence of the sludge phases was also observed. From the obtained results can be concluded that the multiple remelting leads to change of chemical composition, changes in the final microstructure and also increases sludge phases formation. The use of heat treatment T5 led to a positive change of microstructure, while the effect of natural aging is beneficial only to the 3rd remelting.

5

Effects Of T6 Heat Treatment With Double Solution Treatment On Microstructure, Hardness And Corrosion Resistance Of Cast Al-Si-Cu Alloy

Wiengmoon A., Sukchot P., Tareelap N., Pearce J. T. H., Chairuangsri T.

Archives of Metallurgy and Materials

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2015

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Vol. 60, iss. 2A

881--886

EN

Effects of T6 heat treatment with double solution treatment on microstructure, hardness and corrosion resistance of a cast A319 (Al-4.93wt%Si-3.47wt%Cu) alloy were investigated. The T6 heat treatment comprised of the first solution treatment at 500±5°C for 8 h, the second solution treatment in the temperature range of 510 to 530±5°C for 2 h followed by water quenching (80°C), and artificial aging at 170°C for 24 h followed by water quenching (80°C). Microstructure of the alloy was studied by optical microscopy and electron microscopy, Rockwell hardness was measured, and corrosion resistance in 0.1 M NaCl aqueous solution was determined by a potentiodynamic technique. The results revealed that the T6 heat treatment with double solution treatment led to an improvement in corrosion resistance and comparable macrohardness as compared to those obtained from the case of single solution treatment. The second solution treatment at 520°C is the optimum leading to relatively low corrosion current density without substantial drawbacks on breakdown potential or the width of passive range.

PL

W pracy badano wpływ obróbki termicznej T6 połączonej z podwójnym przesycaniem na mikrostrukturę, twardość oraz odporność na korozję stopu A316 (Al-4,93Si-3,47Cu w % wag.) otrzymanego metodą odlewania. Obróbkę termiczną T6 przeprowadzono w następujący sposób: w pierwszej kolejności stop poddano przesycaniu w temperaturze 500±5°C przez 8 godzin, a następnie w zakresie temperatur od 510 do 530±5°C przez 2 godziny, hartowanie wodą (80°C) oraz sztuczne starzenie w 170°C przez 24 godziny i ponowne hartowanie wodą (80°C). Mikrostrukturę stopu badano metodami mikroskopii optycznej i mikroskopii elektronowej. Pomiar twardości stopu wykonano metodą Rockwella. Odporność stopu na korozję w roztworze wodnym 0.1 M NaCl wyznaczono metodą potencjodynamiczną. Otrzymane wyniki wykazały, że obróbka termiczna T6 z podwójnym przesycaniem prowadzi do poprawy makrotwardości oraz odporności materiału na korozję w porównaniu do stopu poddanego pojedynczemu przesycaniu. Stwierdzono także, iż drugie przesycanie w temperaturze 520°C jest optymalne i prowadzi do stosunkowo niskiej gęstości prądu korozyjnego bez znaczących odchyleń potencjału rozkładowego lub szerokości zakresu pasywnego.

6

Analysis of influence of chemical composition of Al-Si-Cu casting alloy on formation of casting defects

Dobrzański L. A., Krupiński M., Zarychta P., Maniara R.

Journal of Achievements in Materials and Manufacturing Engineering

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2007

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Vol. 21, nr 2

53-56

EN

Purpose: A methodology of the computer-aided determining relationship between chemical composition of aluminium alloy and castings quality was presented in the paper. Design/methodology/approach: To resolve the problem artificial neural networks were used. Classification problems were evaluated by the consideration mainly the values of mistakes and correct answers of networks for test data. On the basis of data analyzed by the neural network, which has the best quality classification of chemical composition of tested material, the concentration of alloying elements range, which have an effect on formation casting defects, were developed to eliminate them in the future. Findings: Combining of all methods making use of chemical composition of aluminium alloy and neural networks will make it possible to achieve a better casting quality. Research limitations/implications: The presented issues may be use, among others, for manufacturers of car subassemblies from light alloys, where meeting the stringent quality requirements ensures the demanded service life of the manufactured products. Originality/value: The correctly specified number of chemical composition of aluminium alloy enables such technological process control where the number of castings defects can be reduced by means of the proper correction of the process.

7

Rola składu chemicznego podczas obróbki cieplnej stopów Al-Si-Cu

Kaczorowski M., Krzyńska A.

Krzepnięcie Metali i Stopów

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1998

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nr 36

111--120

PL

Nieustanne dążenie do zmniejszenia masy konstrukcji powoduje wzrost wymagań stawianych materiałom konstrukcyjnym. Dotyczy to również tworzyw odlewniczych, zarówno z grupy stopów Fe jak i Al. Wśród tych ostatnich najpowszechniej stosowanymi są stopy Al-Si często zawierające dodatek Cu i Mg, które umożliwiają ich obróbkę cieplną zwaną umacnianiem wydzieleniowym. W warunkach przemysłowych parametry obróbki cieplnej, takie jak temperatura i czas, są ustalone dla danego stopu pod kątem uzyskania założonych właściwości mechanicznych. Z drugiej strony wiadomo, że każda norma dopuszcza mniejsze lub większe odchylenie od składu chemicznego. [...]