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1

Optimizing the mechanical properties of Al-4.5Cu-xSi alloys through multi-pass friction stir processing and post-process aging

Mostafavi M., Taghiabadi R., Jafarzadegan M.

Archives of Civil and Mechanical Engineering

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2022

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Vol. 22, no. 1

art. no. e11, 2022

EN

The effect of post-process aging on the microstructure and mechanical properties of multi-pass friction stir processed (FSPed) Al-4.5Cu alloy containing Si (1, 3, and 5 wt.%) was studied. According to the results, adding Si improved the fluidity and decreased the porosity content of the alloy. The addition of Si up to 3 wt.% also enhanced the mechanical properties. However, further addition of Si up to 5 wt.% impaired the tensile properties. Applying the first pass of FSP improved the tensile strength and fracture strain of the alloy containing 3 wt.% Si by 25 and 125%, respectively. However, the second and fourth pass of FSP substantially improved the fracture strain, but deteriorated the hardness and tensile strength of the alloy containing 3 wt.% Si. Post-FSP aging at 180 °C for 8 h significantly improved the mechanical properties. For instance, compared to the as-cast condition, the hardness, tensile strength, fracture strain, and toughness of post-aged four-pass FSPed Al-4.5Cu-3Si alloy increased by 107, 108, 175, and 310%, respectively. According to the fractography results, the fracture surface morphology of Al-4.5Cu-3Si alloy changed from a quasi-cleavage mode in as-cast condition to a ductile-dimple fracture mode after post-FSP aging.

2

Optimization of Al-Cu Cast Alloy Composition for Hydraulic Valves

Li Rong, Chen Lunjun, Zeng Qi, Su Ming, Xie Zhiping

Archives of Foundry Engineering

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2020

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Vol. 20, iss. 1

84--94

EN

In order to identify the influence of different Mn, Cd, V and Zr content on the properties of Al-Cu casting alloys in hydraulic valves, orthogonal test methods were used to prepare alloy test bars with different elements and contents. Tensile tests were performed on the test bars so obtained. The microstructure of alloys with different compositions is studied. The results show that adding approximately 0.4% of Mn can not only form a strengthening phase but also reduce the excessive segregation of the matrix along the grain boundary. A Cd content of 0.2% can promote the formation of micro Cd spheres in the softer aluminum matrix. Hard spots increase the wear resistance of the material; however, an excess of Cd will cause element segregation and deteriorate the mechanical properties of the valve body. Zr and V refine the grains in the alloy; however, an excess of these elements will lead to a large area of segregation. If proper heat treatment is lacking, the mechanical properties of the valve body deteriorate.

3

Fluidity Characteristics of A201 and A206 Al-Cu Alloy

Yildirim K., Helvaci M., Gürsoy Ö., Erzi E., Kahruman C., Dispinar D.

Archives of Foundry Engineering

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2018

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Vol. 18, iss. 1

135--138

EN

Al-4.5Cu alloys are widely used in aerospace industries due to their low weight and high mechanical properties. This group of aluminium alloys is known as 2xx series and exhibits the highest mechanical properties however this alloy is known to suffer from feedability and high tendency for hot tearing. Al-Si alloys (3xx) have improved fluidity and better feedability particularly by several modifications such as Ti, B or Sr. Eutectic temperature is decreased and mechanical properties can be enhanced. Yet, the strength values of this alloy group cannot reach the values of 2xx series. Therefore, in this study, the effect of Ag addition on the fluidity of Al-4.5Cu alloy has been investigated. Standard size spiral mould was used. The casting temperature was selected to be 770oC. Five castings were made and Weibull statistical approach was used to evaluate the results. In addition, coating of the die with BN was also investigated. It was found that Ag addition and BN coating of the die revealed the most reproducible, reliable and high fluidity values.

4

Effect of Titanium and Boron on the Stability of Grain Refinement of Al-Cu Alloy

Górny M., Sikora G., Kawalec M.

Archives of Foundry Engineering

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2016

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Vol. 16, iss. 3

35--38

EN

The present research was conducted on thin-walled castings with 5 mm wall thicknesses. This study addresses the effect of the influence of different master alloys, namely: (1) Al-5%Ti-1%B, (2) Al-5%Ti and (3) Al-3%B, respectively on the structure and the degree of undercooling (ΔTα = Tα-Tmin, where Tα - the equilibrium solidification temperature, Tmin - the minimum temperature at the beginning of α(Al) solidification) of an Al-Cu alloy. The process of fading has been investigated at different times spent on the refinement treatment ie. from 3, 20, 45 and 90 minutes respectively, from the dissolution of master alloys. A thermal analysis was performed (using a type-S thermocouple) to determine cooling curves. The degree of undercooling and recalescence were determined from cooling and solidification curves, whereas macrostructure characteristics were conducted based on a metallographic examination. The fading effect of the refinement of the primary structure is accompanied by a significant change in the number (dimension) of primary grains, which is strongly correlated to solidification parameters, determined by thermal analysis. In addition to that, the analysis of grain refinement stability has been shown with relation to different grain refinements and initial titanium concentration in Al-Cu base alloy. Finally, it has been shown that the refinement process of the primary structure is unstable and requires strict metallurgical control.

5

Wpływ miedzi na strukturę pierwotną i przemianę eutektyczną w stopach Al-Cu

Sikora G.

Archives of Foundry Engineering

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2015

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Vol. 15, iss. 4 spec.

113--118

PL

W ramach niniejszej pracy zbadano wpływ miedzi (1-5 % mas.) na strukturę pierwotną i przemianę eutektyczną w stanie wyjściowym jak i modyfikowanym. W tym celu wykonano dwie serie wytopów: wyjściową oraz modyfikowaną, gdzie, jako modyfikatora użyto zaprawy AlTi5B1 w ilości 0,2 % mas. W przypadku serii stopów niemodyfikowanych w całym badanym zakresie zawartości miedzi obserwuje się krystalizację egzogeniczną, z dobrze rozwiniętymi gałęziami dendrytów (ziaren pierwotnych). Badania metalograficzne wykazały zmniejszenie szerokości ziaren kolumnowych ze wzrostem zawartości miedzi. W przypadku serii modyfikowanej obserwuje się transformację z ziaren kolumnowych na równoosiowe podczas krystalizacji (egzogeniczna-endogeniczna). W tym przypadku dendryty (ziarna) nie posiadają dobrze rozwiniętych gałęzi. Wykazano wpływ miedzi na zwiększenie liczby ziaren pierwotnych i zmniejszenie ich średniej średnicy wraz ze wzrostem zawartości miedzi w badanych stopach. [...]

EN

This paper investigated influence of copper content on the primary structure and eutectic transformation in Al-Cu alloys in base and modified states. In this aim two series of alloys was performed: first based and second modified with AlTi5B1 master alloy in amount of 0,2% mass percent. In case of first alloys series it was observed the exogenous crystallization with well expanded second dendrite arm spacing SDAS. The metallographic examinations was shown decrease width of columnar grains with amount of copper. In modified series was observed a transformation from columnar to equiaxed grains during solidification (exogenous-endogenous) process. In this case grains does not have well expanded second arm spacing as well as first series. It has been shown influence of copper on increase grains density and decrease their average diameter. [...]

6

Rozkład wielkości podłoża do zarodkowania heterogenicznego fazy pierwotnej stopu Al-Cu

Lelito J., Gracz B., Żak P. L., Suchy J. S., Szucki M., Malinowski P.

Archives of Foundry Engineering

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2015

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Vol. 15, iss. 4 spec.

83--86

PL

Rozwój komputeryzacji spowodował duży postęp w numerycznym modelowaniu krystalizacji stopów odlewniczych. Możliwe staje się prognozowanie mikrostruktury odlewów. W tym celu konieczna jest znajomość równań opisujących rozkłady wielkości podłoża do zarodkowania heterogenicznego ziaren bądź funkcji gęstości ziaren w zależności od przechłodzenia. W pracy zamieszczono obliczenia dla modelu wykładniczego i eksponencjalnego gęstości ziaren w funkcji przechłodzenia maksymalnego. Dodatkowo przeprowadzono również obliczenia dla logarytmiczno-normalnego rozkładu wielkości podłoża do zarodkowania heterogenicznego. Zasadniczym celem tej pracy jest wyznaczenie w powyższych równaniach, parametrów dopasowania krzepnącego stopu Al-Cu na podstawie badań doświadczalnych zamieszczonych w literaturze [7]. W przypadku logarytmiczno-normalnego rozkładu wielkości podłoża do zarodkowania heterogenicznego, parametry występujące w tym równaniu zostały wyznaczone za pomocą algorytmu numerycznego. Tak wyznaczone rozkłady zostały następnie zestawione na wykresie z danymi eksperymentalnymi w celu ich porównania.

EN

The development of computerization caused a lot of progress in numerical modeling of alloys crystallization. It becomes possible to predict casting microstructure. For this purpose, it is necessary to know the equations describing the size distribution of the substrate to the heterogeneous nucleation of grains or grains density function dependence on supercooling. The paper presents calculations for Oldfield and exponential model of grain density as a function of the maximum supercooling. In addition, calculations were also performed for the log-normal distribution of the substrate size to heterogeneous nucleation of primary phase. The main aim of this work is to determine the fitting parameters of Al-Cu alloy solidifying based on experimental studies published in the literature [7] for above equations. In the case of log-normal size distribution of substrate for heterogeneous nucleation, the parameters present in the equation were determined using a numerical algorithm. Thanks to these schedules were then summarized in the graph of experimental data for comparison.

7

Mathematical and numerical model of directional solidification including initial and terminal transients of the process

Kapturkiewicz W., Burbelko A. A., Fraś E.

Archives of Foundry Engineering

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2008

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Vol. 8, iss. 4

65-70

EN

The, developed in this study, simple model and numerical solution of diffusion growth of the solid phase under the conditions of directional solidification allow for the effect of constituent diffusion in both liquid and solid phase and assume the process run in which (like in reality) the preset parameter is the velocity of sample (pulling velocity) at a preset temperature gradient. The solid/liquid interface velocity is not the process parameter (like it is in numerous other solutions proposed so far) but a function of this process. The effect of convection outside the diffusion layer has been included in mass balance under the assumption that in the zone of convection the mixing is complete. The above assumptions enabled solving the kinetics of growth of the solid phase (along with the diffusion field in solid and liquid phase) under the conditions of diffusion well reflecting the process run starting with the initial transient state, going through the steady state period in central part of the casting, and ending in a terminal transient state. In the numerical solution obtained by the finite difference method with variable grid dimensions, the error of the mass control balance over the whole process range was 1- 2%.

8

The solidification of squeeze cast AlCu4Ti alloy

Zyska A., Konopka Z., Łągiewka M.

Archives of Foundry Engineering

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2007

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Vol. 7, iss. 4

193-196

EN

The results of examining the solidification process of the squeeze cast AlCu4Ti alloy have been presented. A simulation of the alloy solidification has been described for both the equilibrium conditions taking into account squeeze pressure and the non-equilibrium conditions under the assumption of the lack of diffusion in the solid state (Scheil model). Experiments have been held for plate castings squeezed under the pressure ranging from the atmospheric one to the value of 90 MPa. The derivative differential thermal analysis (DDTA) method has been used for determining the phase transition point, solidification rate and the degree of alloy supercooling dependent on the squeeze pressure. It has been found that the solidification rate is increased by almost seven times for squeeze castings as compared with the gravity castings. Squeezing causes also a significant refinement of the alloy dendritic structure and removes gas and shrinkage porosity, characteristic for die castings. The high quality AlCu4Ti-alloy castings can be obtained already at the 30 MPa pressure.

9

Zmiana szerokości strefy kryształów kolumnowych w odlewach krzepnących w polu magnetycznym

Szajnar J., Gawroński J.

Archiwum Odlewnictwa

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2003

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R. 3, nr 8

191--198

PL

W pracy dokonano analizy wpływu zmiennych czynników odlewania w wirującym polu magnetycznym na szerokość strefy kryształów kolumnowych. Badania przeprowadzono na stopach AlCu. Zmiennymi czynnikami odlewania wybrano: prędkość ruchu ciekłego metalu w formie będącą wynikiem działania pola magnetycznego o odpowiedniej indukcji, stężenie nominalne miedzi w stopie AlCu oraz temperaturę zalewania. Wynikiem badań są zależności ujmujące wyżej wymienione czynniki. Na podstawie wyników badań stwierdzono, że uzyskanie zmniejszenia szerokości strefy kryształów kolumnowych wymaga spełnienia dwóch podstawowych czynników: stężenie składnika stopowego w stopie musi być powyżej pewnej minimalnej wartości oraz prędkość strumienia ciekłego metalu przed frontem krystalizacji powinna przekroczyć tzw. prędkość minimalną.

EN

In this work the influence of variables factors of pouring in rotating magnetic field on crystals zone is presented. The investigations were maked on alloys AlCu. The variables factors of pouring were as follows: velocity of traffic liquid metal in mould, concentration nominal coppers on alloy AlCu, and temperature of pouring. Equations of regress with factors above - mentioned were the results of investigations. On the base of results of investigations, it was observed that the reduction of columnar crystals zone demands realization of two basic assumptions: - concentration of component in alloy should be above certain minimum - values; - velocity of stream liquid metal before the front of crystallization should exceed minimum velocity.

10

Krystalizacja stopów Al-Cu w procesie szybkiego chłodzenia

Wierzbicka B.

Krzepnięcie Metali i Stopów

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1998

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nr 38

143--150

PL

Badaniom poddano stopy Al-Cu o różnej zawartości miedzi i do 10% dodatku stopowego. Próbki w trakcie ich krystalizacji gwałtownie schładzano przez zanurzenie w kąpieli wodnej z dodatkiem lodu (metoda tzw. zamrażania). Proces schładzania realizowano z różnych temperatur, rejestrując równocześnie krzywą termiczną. Uzyskany materiał doświadczalny poddano badaniom strukturalnym i opisano mikrostrukturę, przeprowadzono ocenę ilościową, a także dokonano identyfikacji wydzieleń.

EN

Investigations have been concerned with Al-Cu alloys of various copper content and up to 10% of alloying addition. Samples have been rapidly cooled by dipping in water mixed with ice (the so-called freezing method). Thermal curves have been registered for rapid cooling processes being started at various temperatures. Test samples have undergone structural examination and their microstructure has been described, its quantitative assessment has been done and precipitations have been identified.