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1

Analiza możliwości kształtowania rowków za pomocą wysokociśnieniowego strumienia wodno-ściernego w stopie aluminium

Kudelski Rafał

Stal, Metale & Nowe Technologie

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2023

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nr 11-12

30--39

PL

Niekonwencjonalne metody obróbki skrawaniem stały się popularnym rozwiązaniem do obróbki materiałów w przemyśle energetycznym, motoryzacyjnym i lotniczym, szczególnie podczas obróbki materiałów trudnoskrawalnych.

2

Investigations of CrN/TiO2 coatings obtained in a hybrid PVD/ALD method on Al-Si-Cu alloy substrate

Staszuk Marcin

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2023

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Vol. 71, nr 2

art. no. e144622

EN

The paper addresses an important scientific topic from the utilitarian point of view concerning the surface treatment of Al-Si-Cu aluminum alloys by PVD/ALD hybrid coating deposition. The influence of the conditions of deposition of titanium oxide in CrN/TiO2 coatings on their structure and properties, in particular corrosion resistance, were investigated. The TiO2 layer was produced by the atomic layer deposition (ALD) method with a variable number of cycles. Structural investigations were performed using scanning and transmission electron microscopy (SEM and TEM), atomic force microscopy (AFM), and Raman spectroscopy methods. Electrochemical properties were analyzed using potentiodynamic and electrochemical impedance spectroscopy (EIS) methods. The CrN/TiO2 hybrid coating with titanium oxide deposited at 500 ALD cycles showed the best corrosion properties. It was also found that the prerequisite for obtaining the best electrochemical properties was the amorphous structure of titanium oxide in the tested hybrid coatings. The high tribological properties of the tested coatings were also confirmed.

3

Zastosowanie zgrzewania tarciowego z przemieszaniem (FSW) do wykonywania połączeń doczołowych wysokowytrzymałych stopów aluminium stosowanych w przemyśle zbrojeniowym

Kosturek Robert

Stal, Metale & Nowe Technologie

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2022

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nr 9-10

38--41

PL

Otrzymywanie wysokiej jakości połączeń spójnościowych umacnianych wydzieleniowo stopów aluminium stanowi jedną z decydujących batalii na froncie rozwoju współczesnej techniki, będąc istotnym motorem postępu przemysłu motoryzacyjnego, lotniczego i zbrojeniowego.

EN

This paper presents selected results of research concerning AA2519-T62 and AA7075-T651 butt joints produced with the FSW technique, including macroscopic observations, microhardness distributions and tensile tests. The applied welding technique enabled obtaining high-quality welds of the 87% and 77% joint efficiencies for AA2519-T62 and AA7075- -T651 respectively.

4

A study of the properties and development in technology for obtaining multi-component systems of particle reinforced aluminum and titanium alloys

Gumen Olena, Selina Irina, Kruzhkova Mariia

Budownictwo o Zoptymalizowanym Potencjale Energetycznym

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2022

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Vol. 11

17--21

EN

The article analyzes the groundwork on the influence of alloying contaminants on the structure and mechanical properties of aluminum alloys. Aluminum has become widely used in various parts of machine-building due to its physical properties. However, the main task of modern material science is to increase the strength of aluminum alloys. Therefore, today there is the development of materials and alloys based on aluminum with alloying constituents (copper, silicon, magnesium, zinc, mangan), which are administered in aluminum mainly to increase its strength. Especially attractive are properties of aluminum-doped by transition metals, in particular scandium, zirconium, iron, etc. Finally, conclusions are drawn in order to develop a material based on aluminum with increased hardness, durability, and crack resistance.

5

Adjustment of process parameters in the brazing of aluminium heat exchangers

Mirski Zbigniew, Pabian Jarosław

Biuletyn Instytutu Spawalnictwa w Gliwicach

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2022

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Vol. 66, No. 4

9--20

EN

Brazing in tunnel continuous furnaces constitutes the primary technology used when brazing heat exchangers made of the 3XXX series of aluminium alloys. The pure nitrogen-shielded brazing process is performed using non-corrosive flux NOCOLOK. The primary parameters applied during the brazing of aluminium heat exchangers include brazing temperature and time as well as the type and the amount of filler metals. One of the most commonly used brazing metals (having the form of coatings deposited on elements subjected to brazing) is silumin AlSi7.5. All parameters, significantly affecting the quality of the brazing process, enable the prevention of unfavourable physicochemical phenomena such as the dissolution and the erosion of brazed joints. The article presents results of brazing tests performed using normal, hot and very hot temperature profiles. A wedge test discussed in the article (performed using the normal brazing profile and involving metallographic examination) enabled the determination of the capillarity and wettability of the filler metal. The test also revealed the slight dissolution of materials subjected to brazing, yet within acceptable limit values.

PL

Lutowanie twarde w tunelowych piecach przelotowych jest podstawową technologią spajania wymienników ciepła, wytwarzanych ze stopów aluminium serii 3XXX. Lutowanie odbywa się pod osłoną czystego azotu (99,999%) oraz przy oddziaływaniu niekorozyjnego topnika NOCOLOK. Do podstawowych parametrów lutowania aluminiowych wymienników ciepła zalicza się temperaturę i czas lutowania oraz rodzaj i ilość (grubość plateru) stosowanych materiałów dodatkowych. Jako luty, w postaci platerów naniesionych na łączone elementy, są najczęściej używane spoiwa siluminowe, w tym przede wszystkim spoiwo AlSi7,5. Wszystkie parametry mają bardzo istotny wpływ na jakość procesu lutowania, w tym na uniknięcie niekorzystnych zjawisk fizykochemicznych, takich jak roztwarzanie i erozja połączeń lutowanych. W artykule przedstawiono wyniki prób lutowania, stosując profile temperaturowe: normalny, gorący i bardzo gorący. W próbie klinowej, używając normalnego profilu lutowania, na podstawie badań metalograficznych, określono kapilarność i zwilżalność lutu, a także stwierdzono nieznaczne roztwarzanie materiałów lutowanych, w granicach wartości dopuszczalnych.

6

Effect of Filter Type on Mechanical Properties During Aluminium Alloy Casting

Bruna Marek, Galčík Marek

Archives of Foundry Engineering

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2022

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Vol. 22, iss. 3

95--98

EN

The naturally pressurized gating system was used for reoxidation suppression during aluminium alloy casting. A naturally pressurized gating system appears to be a suitable solution to reduce reoxidation processes, which was proven by our previous works. The disadvantage of this system is that without inserting deceleration elements, the melt velocity is supercritical. Therefore, the aim of paper is to find a proper way to reduce the melt velocity, which is the main parameter affecting the scale of reoxidation processes. For the purpose of the melt velocity reduction, labyrinth filters, foam filters and flat filters effect on the melt velocity and the number of oxides were investigated by numerical simulation software in the first stage of the experiment. After simulations observation, the effect of filters on the mechanical properties was investigated by experimental casts. The simulations and experimental casts proved that filters had a positive effect on the melt velocity reduction and it was associated with increased mechanical properties of castings. The best results were achieved by the foam filter.

7

Influence of Fe, Cr, and Cu addition on the microstructure, hardness, and anticorrosion properties of Al-Ni-Y alloys

Babilas Rafał, Młynarek-Żak K., Łoński W., Bukowiec D., Lis M., Kądziołka-Gaweł M., Warski T., Radoń A.

Archives of Civil and Mechanical Engineering

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2022

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Vol. 22, no. 2

art. no. e82, 1--15

EN

This study evaluated the structural changes of Al-Ni-(Fe,Cr,Cu)-Y alloys induced by different cooling states. The aim was to determine the role of Fe, Cr, and Cu addition as well as cooling rate on the structure, hardness and anticorrosion properties of crystalline and nanocrystalline Al-Ni-Y alloys. The impact of the preparation method on the structure of alloys was observed by the broadening of the X-ray diffraction peaks of the alloys in the form of plates, which indicated structure fragmentation at a high cooling rate. The TEM images showed the formation of a structure composed of homogeneously dispersed α-Al nanograins. Phase analysis performed using X-ray diffraction method and Mossbauer spectroscopy revealed that the slowly cooled master alloys were mainly composed of Al23Ni6Y4, Al10Fe2Y, and α-Al phases. The Al10Fe2Y structure was the main Fe-bearing phase in all investigated master alloys. A crystallization mechanism was proposed based on the DTA heating and cooling curves. The pitting corrosion type was identified based on morphology observations after electrochemical tests. Rapid solidification and the addition of chromium and copper improved the microhardness as well as corrosion resistance. The high increase of hardness (289 HV0.1) and corrosion resistance[...]

8

Experimental investigation of the novel dieless clinching process free of blank holder

Qin Denglin, Chen Chao, Zhang Huiyang, Ren Xiaoqiang, Wu Jinliang

Archives of Civil and Mechanical Engineering

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2022

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Vol. 22, no. 1

art. no. e28, 2022

EN

A novel dieless clinching process free of blank holder was proposed in this study. This novel clinching process applied to joining Al5052 sheets under the forming forces from 24 to 54 kN was investigated experimentally. The joint geometrical characteristics, static mechanical strength, energy absorption and failure modes were revealed. From the results, the sound joints can be produced under various forming forces from 24 to 54 kN. With the forming force increasing, the neck thickness was increased continually while the interlock value remained almost constant. On the other hand, the protrusion height of clinched joint was reduced continually with the forming force increasing. Both the tensile strength and shear strength were enhanced with the forming force increasing. Under the forming force of 54 kN, the tensile strength and the shear strength were 1249 and 1107 kN, respectively. In general, a larger joining force leads to a better clinched joint with lower protrusion height and higher mechanical strength.

9

Effect of single roll drive cross rolling on the microstructure, crystallographic texture, and mechanical behavior of Al–Zn–Mg–Cu alloy

Kazemi-Navaee Amir, Jamaati Roohollah, Aval Hamed Jamshidi

Archives of Civil and Mechanical Engineering

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2022

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Vol. 22, no. 1

art. no. e41, 2022

EN

In this work, the effect of single roll drive cross rolling on the microstructure, crystallographic texture, hardness, tensile properties, and fracture behavior of AA7075 aluminum alloy was investigated. It was found that with increasing the thickness reduction, the grain size reduced and the average width of grain for the 40% deformed sample decreased to 3.7 ± 0.4 µm. Due to the nature of the cross-rolling process, several X-type shear bands were observed after 40% deformation. The recrystallization texture is notably intensified to its highest value of 4.4 × R, after only 20% cold deformation due to the occurrence of continuous dynamic recrystallization (CDRX). The intensity of recrystallization texture sharply dropped to its lowest value of 2.7 × R. This was due to the rotation of Goss-orientated new grains in the 20% deformed sample toward copper orientation during 40% rolling. With increasing the thickness reduction, the overall texture intensity significantly reduced owing to the nature of the cross-rolling process in which the rolling direction rotates 90° after each 10% strain. Two texture transitions were observed along τ fiber: rolling (copper) texture to recrystallization (Goss) texture after 20% thickness reduction and recrystallization to the rolling texture after 40% deformation. The hardness and strength increased by increasing the thickness reduction, while the ductility decreased. After a 40% thickness reduction, yield strength significantly increased from 138.3 ± 4.4 MPa (for initial sample) to the highest value of 580.5 ± 11.5 MPa, demonstrating 320% increment, in the 0° direction. This increment for 45° and 90° direction was 265% and 337%, respectively. By 40% rolling, the value of in-plane anisotropy (IPA) remarkably decreased to its lowest value of 3.4% due to texture weakening. With increasing the rolling reduction to 20%, the severity of Portevin–Le Chatelier (PLC) increased in the flow curves due to the occurrence of CDRX and also strengthening of the rotated cube {001} < 110 > and E {111} < 110 > components. With increasing the rolling reduction, the size of cleavage facets and the severity of delamination increased, and the number and depth of dimples decreased.

10

Prediction of filler added friction stir welding parameters for improving corrosion resistance of dissimilar aluminium alloys 5052 and 6082 joints

Sasikumar A., Gopi S., Mohan Dhanesh G.

Advances in Materials Science

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2022

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Vol. 22, nr 3(73)

79--95

EN

The aluminium alloys 5052 and 6082 are extensively used in manufacturing lighter structural members, having improved strength and resistance to corrosion. Magnesium (Mg) and Chromium (Cr) powder were the filler materials selected for enhanced corrosion protection properties in this investigation. Friction stir welding (FSW) process parameters viz., spindle speed, welding speed, shoulder penetration, the centre distance between the holes and filler ratio are used to forecast the minimum corrosion rate from different weld regions of AA5052-AA6082 dissimilar joints. Response surface methodology based on a central composite design was used to evolve the mathematical models and estimate dissimilar FSW joints’ corrosion rates. Response optimization shows that the minimum corrosion rate was achieved by the welding parameters of spindle speed 1000 rev/min, welding speed 125 mm/min, holes spacing of 2 mm and filler ratio 95% of Mg and 5% of Cr.

11

Stopy aluminium na świecie (obróbki skrawaniem)

Pałka Tomasz

Stal, Metale & Nowe Technologie

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2021

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nr 1-2

12--15

PL

Stopy aluminium stanowią istotną grupę wśród materiałów konstrukcyjnych wytwarzanych na świecie. Szacuje się, że w krajach wysoko rozwiniętych zapotrzebowanie na ten surowiec stale się zwiększa, a ilość produkowanego aluminium jest jednym z wyznaczników uprzemysłowienia danego regionu.

XX

Aluminium alloys are an important group among construction materials produced in the world. It is estimated that in highly developed countries the demand for this raw material is constantly increasing and the amount of produced aluminium is one of the determinants of the industrialisation of a given region.

12

Metoda melt-spinning w wytwarzaniu amorficznych stopów aluminium

Młynarek-Żak Katarzyna, Lis Mateusz, Babilas Rafał

LAB Laboratoria, Aparatura, Badania

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2021

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R. 26, nr 4

38--40

13

Effect of arc stud welding parameters on the microstructure and mechanical properties of AA6061 and AA5086 aluminium alloys

Razzaq M. K. A., Abood A. N.

Journal of Achievements in Materials and Manufacturing Engineering

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2021

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Vol. 108, nr 1

24--34

EN

Purpose: This paper aims to investigate the effect of arc stud welding (ASW) process parameters on the microstructure and mechanical properties of AA6061-T6 and AA5086-H116 joint. Design/methodology/approach: ASW process was done with argon as a shielding gas. Optical microscope (OM), scanning electron microscope (SEM), and X-Ray Diffraction (XRD) were employed to investigate the influence of welding current, welding time, and gas flow-rate on the microstructure of the fusion zone (FZ). Torque strength and Microhardness tests were used to evaluate the mechanical properties of the welded joints. Findings: OM and SEM showed a cellular dendritic structure with equiaxed zone and columnar dendritic are forming at welding zone and weld interface. XRD analysis showed the precipitation of Mg2Si and Al3Mg2 in the similar and dissimilar joints. Similar ASW of AA6061-T6/AA6061-T6 recorded 19 N.m torque strength, while dissimilar welding of AA6061-T6/AA5086-H116 registered 23 N.m. With increasing heat input, grains in Fusion Zone (FZ) and Heat Affected Zone (HAZ) coarsen and the hardness in both zones decreased. The hardness of similar weldments indicated a remarkable softening of FZ, while lower hardness values were registered in HAZ of dissimilar weldments. Softening of both weldments is due to the dissolution of the strengthening precipitates. Hot cracks exist with similar weldments, while no cracks evidence with dissimilar weldments. Research limitations/implications: The main challenge in this work was how to minimize porosity level and how to avoid hot crack in the FZ. Practical implications: The application of ASW with ceramic ferrule has an important role in different production areas such as; automobile industry, aircraft applications, and appliances industry. Originality/value: Study the effect of welding current, welding time, and gas flow-rate of ASW process on microstructure and mechanical properties of AA6061-T6 and AA5086-H116 joint.

14

Study of the influence of chemical elements and production technology parameters on aluminium sheets properties designed for bottle closures drawing process

Rutecki Paweł, Muzykiewicz Wacław, Sulewski Leszek

Inżynieria Materiałowa

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2021

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Vol. 42, nr 2-3

16--23

EN

Aluminium sheets designed for bottle closure production must be characterized with enhanced drawability and highly homogeneous properties ensuring problem-free production process with stable technological scrap level. Closure-stock material shall be produced in very narrow set of mechanical properties and should be characterized with thermal resistance in paint hardening process. This work presents results of study carried out on innovative aluminium alloy produced on the basis of post-consumed and post-produced scrap recycling. Hot-rolled strips with entry thickness 4.5 mm were rolled down to final thickness 0.225 mm in cold rolling and intermediate annealing process. Then cold-rolled sheets were undergone thermal process as simulation of paint hardening cycle. On the basis of mechanical properties, microstructure and technological tests results, influence of additional chemical elements added to aluminium alloys in secondary remelting process on properties of sheets designed for caps deep drawing process was determined. It was stated that additional chemical elements added to aluminium alloys in secondary remelting process increases hardening mechanism (grain size refining, solid solution strengthening, strain hardening) that reflects on higher sheets strength without any negative effects on formability and drawability.

PL

Blachy ze stopów aluminium do produkcji zakrętek muszą charakteryzować się wysoką podatnością do głębokiego tłoczenia i wysoką jednorodnością własności, zapewniającą bezproblemowy przebieg procesu tłoczenia z powtarzalną, zaplanowaną wielkością odpadu technologicznego. Materiał na zakrętki powinien posiadać stabilny w wąskim zakresie poziom własności mechanicznych, a także wysoką odporność termiczną w procesie cieplnego utrwalania lakieru. W pracy przedstawiono wyniki badań, wykonanych na nowatorskim stopie aluminium, który zaprojektowany został na bazie pełnego recyklingu poamortyzacyjnych oraz poprodukcyjnych złomów aluminiowych. Blachy walcowano na zimno na grubość finalną 0,225 mm z grubości początkowej wsadu po walcowaniu na gorąco 4,5 mm (z wykorzystaniem obróbki cieplnej międzyoperacyjnej), a następnie poddano procesowi termicznej obróbki, symulującej proces utwardzania lakieru. Na podstawie badań własności mechanicznych, obserwacji struktury materiału oraz badań technologicznych blach określono wpływ zawartości pierwiastków stopowych (wprowadzonych do stopu w procesie wtórnego przetopu) na własności blach przeznaczonych do tłoczenia zakrętek. Wykazano, że wprowadzenie do metalu dodatkowych pierwiastków stopowych drogą wtórnego przetwórstwa powoduje zwiększenie udziału mechanizmów umocnienia (rozdrobnienie ziarna, umocnienie roztworowe, umocnienie odkształceniowe), co przekłada się na wzrost własności wytrzymałościowych blach do głębokiego tłoczenia, bez obniżenia ich własności plastycznych.

15

On rough set theory on achieving high quality cable material production by green low carbon technology

Shuai Guoliang, Li Zhen, Zhang Diantao, Elhefnawey Maged, Li Li

Ecological Chemistry and Engineering. S

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2021

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Vol. 28, nr 1

49--59

EN

As the second largest machinery industry, the energy-intensive cable industry not only creates a lot of economic value but also consumes a lot of energy. It is an inevitable requirement to promote the technological development of the industry in the new era to improve the quality and efficiency and realise industrial energy-saving and consumption reduction. In order to obtain good strength and conductivity, the metal rods of cable are usually heat-treated for several hours or even several days after the rods are extruded, this is a major energy consuming process in traditional production. Based on the background, this study adopted the energy-saving equal-channel angular pressing (ECAP) technology to replace the traditional heating treatment process, and converted the simple heat conduction with thermo-mechanical energy transfer, so as to realise the good strength and conductivity matching of the cable aluminum alloy material. In this study, energy-saving ECAP technology is used to replace the traditional heat treatment process, and heat-mechanical energy transfer is used to replace the simple heat conduction, so as to achieve good strength and conductivity matching of cable aluminium alloy material. The results show that the suitable ECAP process routes can improve the microstructure of aluminum alloy with higher strength and conductivity than the traditional heating process. The research results can be used for technology upgrading and low carbon production in cable industry due to the significantly time reduction of the energy-consuming heat treatment and the high-efficient obtainment of high-quality production.

16

The Leading Role of Aluminium in the Growing Production of Castings Made of the Non-Ferrous Alloys

Soiński M. S., Jakubus A.

Archives of Foundry Engineering

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2021

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Vol. 21, iss. 3

33--42

EN

The paper presents changes in the production volume of castings made of non-ferrous alloys on the background of changes in total production of casting over the 2000-2019 period, both on a global scale and in Poland. It was found that the dynamics of increase in the production volume of castings made of non-ferrous alloys was distinctly greater than the dynamics of increase in the total production volume of castings over the considered period of time. Insofar as the share of production of the non-ferrous castings in the total production of castings was less than 16% during the first two years of the considered period, it reached the level of 20% in the last four years analysed. This share, when it comes to Poland, increased even to the greater degree; it grew from about 10% of domestic production of castings to over 33% within the regarded 2000-2019 period. The greatest average annual growth rate of production, both on a global scale and in Poland, was recorded for aluminium alloys as compared with other basic non-ferrous alloys. This growth rate for all the world was 4.08%, and for Poland 10.6% over the 2000-2019 period. The value of the average annual growth rate of the production of aluminium castings in Poland was close to the results achieved by China (12%), India (10.3%) and the South Korea (15.4%) over the same period of time. In 2019, the total production of castings in the world was equal to about 109 million tonnes, including over 21 million tonnes of castings made of non-ferrous alloys. The corresponding data with respect to Poland are about 1 million tonnes and about 350 thousand tonnes, respectively. In the same year, the production of castings made of aluminium alloys was equal to about 17.2 million tonnes in the world, and about 340 thousand tonnes in Poland.

17

Structural Characterization of Rapidly Solidified Al71Ni24Fe5 Alloy

Młynarek Katarzyna, Czeppe T., Babilas R.

Archives of Foundry Engineering

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2021

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Vol. 21, iss. 3

90--95

EN

The influence of rapid solidification from the liquid state on the structure of Al71Ni24Fe5 alloy was studied. The samples were prepared by induction melting (ingots) and high pressure die casting into a copper mold (plates). The structure was examined by X-ray diffraction (XRD), light microscopy and high resolution transmission electron microscopy (HRTEM). The mechanism of crystallization was described on the basis of differential scanning calorimetry (DSC) heating and cooling curves, XRD patterns, isothermal section of Al-Ni-Fe alloys at 850°C and binary phase diagram of Al-Ni alloys. The fragmentation of the structure was observed for rapidly solidified alloy in a form of plates. Additionally, the presence of decagonal quasicrystalline phase D-Al70.83Fe9.83Ni19.34 was confirmed by phase analysis of XRD patterns, Fast Fourier Transform (FFT) and Inverse Fast Fourier Transform (IFFT) of transmission electron microscopy images. The metastable character of D-Al70.83Fe9.83Ni19.34 phase was observed because of the lack of thermal effects on the DSC curves. The article indicates the differences with other research works and bring up to date the knowledge about Al71Ni24Fe5 alloys produced by two different cooling rates.

18

Heat Treatment of AlSi7Mg0.3 Aluminium Alloys with Increased Zirconium and Titanium Content

Kantoriková E., Kuriš M., Pastirčák R.

Archives of Foundry Engineering

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2021

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Vol. 21, iss. 2

89--93

EN

The paper compares changes in the structure and mechanical properties due to the synergistic effect of alloying elements Zr and Ti. It is assumed that by increasing the content of Zr and Ti in the aluminium alloy, better mechanical properties will be achieved. Paper focuses on description of the differences between the samples casted into the shell mold and the metal mold. Main difference between mentioned molds is a different heat transfer coefficient during pouring, solidification and cooling of the metal in the mold. The main goal was to analyse the influence of Zr and Ti elements and compare the mechanical properties after the heat treatment. Curing and precipitation aging were used during the experiment. The effect of the elements on AlSi7Mg0.3 alloy created differences between the excluded Zr phases after heat treatment. Evaluation of the microstructure pointed to the decomposition of large predominantly needle Zr phases into smaller, more stable formations.

19

Comparing of High-Cycle Fatigue Lifetimes in Un-corroded and Corroded Piston Aluminum Alloys in Diesel Engine Applications

Azadi M., Aroo H., Azadi M., Parast M. S. A.

Archives of Foundry Engineering

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2021

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Vol. 21, iss. 1

89--94

EN

Diesel engine components in the combustion chamber have been exposed to cyclic loadings under environmental effects, including high temperatures and corrosive fluids. Therefore, knowing the corrosion-fatigue behavior of materials is essential for designer engineers. In this article, pure fatigue and corrosion-fatigue behaviors of the piston aluminum alloy have been experimentally investigated. For such an objective, as-cast and pre-corrosive standard samples were tested by the rotary bending fatigue machine, under 4 stress levels. Some specimens were exposed to the corrosive fluid with 0.00235 % of the sulfuric acid for 100 and 200 hours. The results showed higher weight losses for 200 hours immersion times. As another result, it could be concluded that the lifetime decreased in pre-corrosive samples for both 100 and 200 hours of the immersion time, compared to that of as-cast specimens. However, such a lifetime reduction was more significant for 200 hours of the immersion time, especially within the high-cycle fatigue regime (or lower stress levels). Under high stress levels, both pre-corrosive sample types had almost similar behaviors. The field-emission scanning electron microscopy images of specimen fracture surfaces indicated that the brittle region of the fractured surface was larger for specimens after the 200 hours of corrosion-fatigue testing than the other specimen.

20

Casting Quality Improvement by Gating System Optimization

Bruna M., Galčík M.

Archives of Foundry Engineering

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2021

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Vol. 21, iss. 1

132--136

EN

One of the main reason for decreased internal homogeneity of aluminium alloy castings is reoxidation. The resulting products of reoxidation are doubled oxides, so called "bifilms". Submitted paper deals with optimization of gating system design in order to reduce reoxidation processes taking place in mold cavity. Experimental work compares and evaluates three gating systems designs based on non-pressurized and naturally pressurized principles. Unconventional spin trap extension of runner was used in third design. Among the evaluated aspects were: mechanical properties, hot tearing index, visual inspection of average porosity amount, numerical simulation of velocity, turbulence and oxide amount. Paper aim is also to clarify the reoxidation phenomenon by visualization with the aid of ProCAST numerical simulation software. Results of mechanical properties and hot tear index clearly confirmed the positive effect of the naturally pressurized gating system with applied element for velocity reduction.