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PL
W ostatnich latach obserwuje się znaczny wzrost użycia bezzałogowych statków powietrznych (BSP) w licznych zastosowaniach komercyjnych, a także wojskowych. Obecnie szacuje się, że na świecie istnieje przeszło 10 mln tego typu obiektów, wykorzystywanych od celów od hobbystycznych po profesjonalne, których wartość przekracza wiele milionów dolarów. BSP, zwane powszechnie dronami muszą cechować się małą masą i dużą sprawnością układu napędowego i zasilania, które pozwalają na długi czas nieprzerwanej pracy w powietrzu zwiększając obszar potencjalnych zastosowań. Jest to szczególnie istotne w przypadku obiektów latających używanych w zastosowaniach profesjonalnych. W zależności od zastosowania i liczności serii, do ich budowy wykorzystuje się wiele różnych materiałów w szczególności kompozytów. Jednakże bezzałogowe aparaty latające używane do celów militarnych, a także komercyjnych, np. w transporcie i rolnictwie muszą dodatkowo cechować się wytrzymałą i stabilną konstrukcją pozwalającą na przenoszenie dużych obciążeń. Z tej przyczyny coraz częściej do budowy BSP używa się stopów metali lekkich w szczególności aluminium, magnezu i tytanu. Ważnym argumentem przemawiającym za używaniem stopów metali lekkich są również względy ekologiczne gdyż niedostatecznie jeszcze są rozwinięta procesy recyklingu materiałów kompozytowych.
EN
In recent years, there has been a significant increase in the use of unmanned aerial vehicles(UAV) in numerous commercial as well as military applications. Currently, it is estimated that there are more than 10 million such objects in the world, used for purposes ranging from hobby to professional, with a value exceeding many millions of dollars. UAV, commonly referred to as drones, must be characterized by low weight and high efficiency of the propulsion and power systems that allow for long periods of continuous operation in the air increasing the area of potential applications. This is especially important for flying objects used in professional applications. Depending on the application and the number of series, many different materials are used for their construction, especially composites. However, unmanned aerial vehicles used for military as well as commercial purposes, such as transport and agriculture, must additionally feature a robust and stable design to carry heavy loads. For this reason, lightweight metal alloys, in particular aluminum, magnesium and titanium, are increasingly being used to build UAV. An important argument for the use of light alloys are also ecological considerations as recycling processes for composite materials are still underdeveloped.
EN
In the present research, the wear behaviour of magnesium alloy (MA) AZ91D is studied and optimized. MA AZ91D is casted using a die-casting method. The tribology experiments are tested using pin-on-disc tribometer. The input parameters are sliding velocity (1‒3 m/s), load (1‒5 kg), and distance (0.5‒1.5 km). The worn surfaces are characterized by a scanning electron microscope (SEM) with energy dispersive spectroscopy (EDS). The response surface method (RSM) is used for modelling and optimising wear parameters. This quadratic equation and RSM-optimized parameters are used in genetic algorithm (GA). The GA is used to search for the optimum values which give the minimum wear rate and lower coefficient of friction. The developed equations are compared with the experimental values to determine the accuracy of the prediction.
PL
W artykule przedstawiono wyniki badań dotyczące porównania parametrów struktury geometrycznej powierzchni (SGP) próbek ze stopu magnezu AZ31 po polerowaniu oraz po wytworzeniu na ich powierzchniach różnego typu biokompatybilnych powłok ochronnych. Zakres prezentowanych badań obejmował proces przygotowania próbek do ich cięcia metodą WEDM, polerowania krążkami ściernymi, chemicznego trawienia oraz modyfikację ich powierzchni poprzez wytworzenie biopolimerowych powłok ochronnych metodą chemicznego osadzania z fazy gazowej CVD.
EN
In this paper the results of investigations concerning the comparison of surface geometric structure parameters of samples made of magnesium alloy AZ31 were presented. The samples were polish and coated of various types of biocompatible protective coatings. The scope of presented studies included the process of sample preparation by WEDM cutting, abrasive disc polishing, chemical pickling and modification of their surface by producing biopolymer protective coating by chemical deposition from gas phase (CVD).
4
Content available Fatigue Properties of AZ31 and WE43 Magnesium Alloys
EN
The paper presents low-cycle fatigue (LCF) characteristics of selected magnesium alloys used, among others, in the automotive and aviation industries. The material for the research were bars of magnesium alloys AZ31 and WE43 after hot plastic working. Due to their application(s), these alloys should have good/suitable fatigue properties, first of all fatigue durability in a small number of cycles. Low-cycle fatigue tests were carried out on the MTS-810 machine at room temperature. Low-cycle fatigue trials were conducted for three total strain ranges Δεt of 0.8%, 1.0% and 1.2% with the cycle asymmetry factor R = –1. Based on the results obtained, fatigue life characteristics of materials, cyclic deformation characteristics σa = f(N) and cyclic deformation characteristics of the tested alloys were developed. The tests have shown different behaviors of the tested alloys in the range of low number of cycles. The AZ31 magnesium alloy was characterized by greater fatigue life Nf compared to the WE43 alloy.
EN
The paper presents the susceptibility of AE44 magnesium alloy to electrochemical corrosion and stress corrosion cracking (SCC). The evaluation of the intensity of the interaction of the corrosive environment was carried out using the corrosion tests and the Slow Strain Rate Test (SSRT). Corrosion tests performed in 0.1 M Na2 SO4 solution (immersion in solution and under cathodic polarization conditions) revealed that the layer of corrosion products was much thicker after immersion test. The results of SSRT showed that the AE44 alloy deformed in the solution was characterized by higher plasticity compared to the alloy deformed in the air after immersion in solution. Moreover, the fractures were characterized by different morphology. In the case of an alloy deformed in the solution under cathodic polarization many microcracks on the fracture were observed, which were not observed in the case of the alloy deformed in the air.
EN
The results of the Charpy impact test of AE-type magnesium alloys produced by the high pressure die casting method are presented. Three alloys with different weight fractions of rare earth elements (RE; e.g. 1, 3 and 5 wt%) and the same mass fraction of aluminium (5 wt%) were prepared. The casts were fabricated using a typical cold chamber high pressure die casting machine with a 3.8 MN locking force. Microstructural analyses were performed by means of a scanning electron microscope (SEM). The impact strength (IS) was determined using a Charpy V hammer with an impact energy equal to 150 J. The microstructure of the experimental alloys consisted of an [alpha]-Mg solid solution and Al11RE3, Al10Ce2Mn7 and Al2RE intermetallic compounds. The obtained results show the significant influence of the rare earth elements to aluminium ratio on the impact strength of the investigated materials. Lower the RE/Al ratio in the chemical composition of the alloy results in a higher impact strength of the material.
EN
The present study demonstrates the friction stir welding (FSW) process can be used as a mechanical alloying tool to fabricate a solid solution. An attempt has been taken for alloying the AM20 Mg base matrix using Zn at the weld zone during friction stir welding. Successful joints with sound mechanical properties and enhanced quality attributes are observed in the welds. Use of Zn alloying element at the nugget zone, the joint efficiency reached 90% to that of the base material and also which is about 25% more than the strength obtained in the case of without alloying element set of experiments. The addition of Zn alloy to Mg substrate forms Mg–Zn binary solid solution reinforcing intermetallic compounds, namely MgZn and Mg7Zn3 resulting in improved joint properties. This research work also reports the investigative outcomes, namely flow in the joint area, metallurgical deviation, microstructural modification, and diffusion of the constituent alloying element during the welding process. The targeted objective was effectively accomplished and the Zn alloyed stir area can fulfil the required application. The findings from the selective alloying process may be relevant for the implementation of industrial users over Mg alloys using a FSW process with better weldability and improved strength.
EN
The thermochemical treatment applied to improve the surface properties of AZ91 consisted in heating the material in contact with AlSi10Mg powder at 445 oC for 30 min. During heat treatment process the powder was held under pressure to facilitate the diffusion of the alloying elements to the substrate and, accordingly, the formation of a modified layer. Two pressures, 1 MPa and 5 MPa, were tested. The resultant layers, containing hard Mg2Si and Mg17Al12 phases, were examined using an optical microscope and a scanning electron microscope equipped with an energy-dispersive X-ray spectrometer (EDS). The experimental data show that the layer microstructure was dependent on the pressure applied. A thicker, three-zone layer (about 200 μm) was obtained at 1 MPa. At the top, there were Mg2Si phase particles distributed over the Mg17Al12 intermetallic phase matrix. The next zone was a eutectic (Mg17Al12 and a solid solution of Al in Mg) with Mg2Si phase particles embedded in it. Finally, the area closest to the AZ91 substrate was a eutectic not including the Mg2Si phase particles. By contrast, the layer produced at a pressure of 5 MPa had lower thickness of approx. 150 μm and a two-zone structure. Mg2Si phase particles were present in both zones. In the upper zone, Mg2Si phase particles were regularly distributed over the Mg17Al12 intermetallic phase matrix. The lower zone, adjacent to the AZ91, was characterized by a higher volume fraction of Mg2Si phase particles distributed over the matrix composed mainly of Mg17Al12. The alloyed layers enriched with Al and Si had much higher hardness than the AZ91 substrate.
PL
W artykule przedstawiono analizę struktury złącza stop aluminium (PA38)–stop magnezu (AZ31) wytworzonego metodą zgrzewania dyfuzyjnego. Za pomocą mikroskopu optycznego i elektronowego mikroskopu skaningowego przeprowadzono szczegółowe badania metalograficzne. Skład chemiczny strefy złącza określono metodą mikroanalizy rentgenowskiej (EDS). Wykonano również pomiary mikrotwardości metodą Vickersa łączonych materiałów i strefy złącza. W wyniku procesu zgrzewania uzyskano trwałe połączenie. Strefa złącza, o grubości ok. 50 µm, miała budowę dwuwarstwową. Od strony stopu PA38 w złączu zidentyfikowano grubszą warstwę (ok. 40 µm) fazy międzymetalicznej Al3Mg2, od strony stopu AZ31 cieńszą warstwę (ok. 10 µm) fazy międzymetalicznej Mg17Al12. W mikrostrukturze strefy złącza od strony stopu PA38 na tle osnowy fazy Al3Mg2 stwierdzono obecność drobnych cząstek fazy Mg2Si. Od strony stopu AZ31, na tle fazy Mg17Al12, obserwowano lokalnie iglaste cząstki fazy Al-Mn-Si. Na podstawie pomiarów mikrotwardości stwierdzono, że strefa złącza zbudowana głównie z faz międzymetalicznych Mg-Al charakteryzuje się kilkukrotnie wyższą mikrotwardością w porównaniu z łączonymi stopami.
EN
This paper presents the results of the microstructure investigation of the aluminium alloy (PA38) – magnesium alloy (AZ31) joint fabricated by diffusion bonding. The structure of the bonding zone was examined using optical microscopy and scanning electron microscopy. The chemical composition of the bonding zone was determined by energy dispersive X-ray microanalysis. The microhardness measurements of the alloys and the bonding zone was also conducted. As a result of the diffusion bonding process the alloys were joined together. The bonding zone with a thickness of about 50μm had two-layer structure. In the bonding zone the thicker layer (about 40μm) of Al3Mg2 intermetallic phase was observed on the PA38 alloy side. The thinner layer (about 10 μm) of Mg17Al12 intermetallic phase was observed on the AZ31 alloy side. In the area of the bonding zone close to the PA38 alloy fine particles of Mg2Si phase were found in the matrix of Al3Mg2. In the bonding zone close to the AZ31 alloy locally a needle-shaped particles of the Al-Mn-Si phase were observed over the Mg17Al12 phase matrix. The results of microhardness measurement revealed that the bonding zone composed mainly of Mg-Al intermetallic phases layers had much higher microhardness than the joined alloys.
PL
W pracy zaproponowano wykonanie lekkiego materiału wielowarstwowego składającego się z trzech warstw, w którym zewnętrzne warstwy stanowiło aluminium w gatunku 1050A, natomiast środkowa warstwa wykonana była ze stopu AZ31. Przygotowany materiał wielowarstwowy poddano odkształceniu za pomocą metody ARB w 4 przepustach przy temperaturze 400°C. Przyjęto, że początkowa grubość pakietu wynosiła 3 mm (po 1 mm dla każdego komponentu). Walcowanie zrealizowano w walcarce laboratoryjnej duo D150 z zastosowaniem symetrii i asymetrii prędkości obrotowych walców. W pracy wykazano, że wprowadzenie asymetrii do metody ARB dla badanego materiału Al-Mg-Al, wpływa na rozdrobnienie struktury w porównaniu do procesu symetrycznego.
EN
The study has proposed the production of a lightweight multilayered material composed of three layers, in which the external layers is made up by aluminium in grade 1050A, while the central layer is made of the alloy AZ31. The prepared multilayered material was subjected to deformation by the ARB method in 4 rolling passes. The initial packet thickness was assumed to be 3 mm (1 mm for each component), and the rolling process was conducted at a temperature of 400°C. The rolling was carried out on a D150 laboratory two-high mill equipped with individual working roll drives, which enabled a rotational roll speed asymmetry to be introduced into the rolling process. As a result of the rolling carried out, a multilayered material was obtained, which was characterized by a refined structure.
11
Content available remote Odporność odlewniczego stopu magnezu AZ91 na korozję elektrochemiczną
PL
W artykule przedstawiono wyniki testów odporności na korozję elektrochemiczną odlewniczego stopu magnezu AZ91. Obserwacjom poddano materiał rodzimy i złącza spawane wykonane metodą TIG (141). Jako kryterium odporności na korozję elektrochemiczną przyjęto ubytek masy i czas korozji przy określonych stężeniach roztworu kwasu H2SO4. Stwierdzono, że wzrost stężenia roztworu kwasu wpływa znacząco na szybkość korozji stopu powodując tym samym większą degradację jego powierzchni i większy ubytek masy. Zauważono również, że prędkość korozji maleje w przypadku wydłużenia czasu eksperymentu. Po czasie 72 h prędkość ta spada poniżej 0,1g/(cm2•doba), co spowodowane jest hamowaniem korozji w wyniku zobojętniania się roztworu kwasu.
EN
The article presents the results of AZ91 cast magnesium alloy resistance to electrochemical corrosion. The basic material and welding joints obtained by TIG method (141) were evaluated. The mass loss and corrosion time at specific concentrations of the H2SO4 acid solution were assumed as a criterion of resistance to electrochemical corrosion. It was found that an increase in the acid solution concentration significantly affects the rate of corrosion of alloy, thus causing a greater degradation of its surface and a higher mass loss. It was also noticed that the corrosion rate decreases when the experiment time is extended. After 72 h, this speed drops below 0.1 g/(cm2•day), which is caused by the inhibition of the corrosion as a result of the neutralization of the acid solution.
PL
Wykorzystanie stopów magnezu w przemyśle motoryzacyjnym jest utrudnione, gdyż procesy gięcia i tłoczenia muszą być prowadzone w podwyższonych temperaturach. Drugim przeciwwskazaniem jest niewielka sztywność elementów magnezowych. W pracy przedstawiono wyniki badań dynamicznego zgniatania magnezowych elementów energochłonnych. Zastosowanie elementów usztywniających w postaci pianki aluminiowej pozwala na pochłanianie dużej energii właściwej (energia podzielona przez masę). W pracy wykazano, że energia właściwa pochłaniana przez magnezowe crash-boxy może być większa niż w przypadku elementów wykonanych ze stali HC380.
EN
The use of magnesium alloys in automotive industry is difficult, because the processes of bending and pressing must be carried out at an elevated temperatures. The second contraindication is a low stiffness of magnesium elements. Following paper presents results of dynamic crushing of magnesium energy-absorbing elements. The use of aluminum foam as stiffening elements allows to absorb high specific energy (absorbed energy divided by specimen mass). The paper has shown that the specific energy absorbed by the magnesium crash-boxes is greater than specific energy absorbed by crash-boxes made of HC380 steel.
EN
This paper deals with the evaluation of changes in hardness of magnesium alloys during precipitation hardening that are nowadays widely used in different fields of industry. It focuses exactly on AZ31, AZ61 and AZ91 alloys. Observing material hardness changes serves as an effective tool for determining precipitation hardening parameters, such as temperature and time. Brinell hardness measurement was chosen based on experimental needs. There was also necessary to make chemical composition analysis and to observe the microstructures of tested materials. The obtained results are presented and discussed in this paper.
PL
W pracy wykonano teoretyczną analizę procesu wyciskania przeciwbieżnego z obrotowym narzędziem stopu AZ31. Symulacje komputerowe przeprowadzono dla parametrów plasto-meru skrętnego STD810. Modyfikacja klasycznego sposobu wyciskania przeciwbieżnego polegała na zastosowaniu obrotowego stempla. Uzyskane wyniki badań teoretycznych wykazały, że zastosowanie zmodyfikowanej metody wyciskania przeciwbieżnego powoduje pojawienie się w odkształcanym materiale naprężeń stycznych, co wpływa na aktywowanie dodatkowych mechanizmów odkształcenia. W pracy do modelowania numerycznego procesu wyciskania przeciwbieżnego stopu AZ31 zastosowano program komputerowy Forge2011®.
EN
In this work theoretical analysis of the backward extrusion with a rotary die of the AZ31 alloy has been performed. Computer simulations were conducted for the parameters of the torsion plastometer STD 810. The modification of the classical backward extrusion method involved the application of a rotatry punch. The results of theoretical research have confirmed that the use of the modified method of backward extrusion causes the appearance of shear stress in deformed material, which affects the activation of additional mechanisms of deformation. For numerical modelling of the AZ31 alloy backward extrusion process, the Forge2011® computer program was used in the study.
EN
A cast AZ91 magnesium alloy was processed via backward extrusion (BE) method at different temperatures of 250, 350 and 450°C. Metallography investigations were conducted at three different regions of BE-processed cup (wall, bottom and flow channel). The main feature observed at the wall of the BE cup was mechanical twins, the frequency of which was decreased by increasing the process temperature. Flow localization in the form of shear banding occurred within the flow channel at all deformation temperatures. The bottom of the BE-processed cup at 250°C exhibited coarse initial grains along with continuous network of eutectic phase at the grain boundaries. However, increasing the process temperature to 350 and 450°C led to the fragmentation of the γ-Mg17Al12 network down to the fine particles, where a considerable grain refinement was also traced particularly at 450°C. Furthermore, shear punch testing method was employed to evaluate the room temperature mechanical properties of the backward extruded specimens. The results show that BE-processed material would benefit from higher strength compared to the as-received material; however, the ductility follows different trends depending on the deformation temperature.
EN
In this work, the effect of the microstructure on corrosion behavior of selected Mg- and Al-based as cast alloys, was evaluated. The electrochemical examinations were carried out, and then a morphology of corrosion products formed due to local polarization on materials surface, was analyzed. It was documented that the presence of Mg2Si phase plays an important role in the corrosion course of Mg-based alloy. A selective etching was observed in sites of Mg2Si precipitates having “Chinese script”- like morphology. Analogous situation was found for Al-based alloy, where the key role was played by cathodic θ-CuAl2 phase.
EN
The results of estimation of home scrap addition in charge influence on durability and wear of casting instrumentation life in the high-pressure casting technology using the hot chamber machine of alloy of AZ91 are presented. The wear of the following elements of the casting instrumentation so-called "casting set" as: syphon, plunger, sliding-rings, nozzle and injection moulding nozzle was estimated. A wear was estimated quantitative by registering the number of mould injections for different charges to the moment of element damage supervision. A damage had to be at such level that liquidated an element from further exploitation and necessary was an exchange on new or regeneration. In a final result allowed it the detailed determination of durability of the applied rigging elements in dependence on the type of the applied type of melt. It is noticed, that together with the increase of home-scrap participation in the charge wear of pressure machine instrumentation elements increases.
EN
The effectiveness of cast iron spheroidization with FeSiMg master alloy by the traditional method and using a reaction chamber placed in the cavity of foundry mould was compared. The method of cast iron treatment in mould cavity using a reaction chamber is an innovative technology developed by the Foundry Research Institute in Krakow. The effectiveness of the spheroidization process carried out by both methods was checked on a series of test castings. The article also presents the results of metallographic examinations and mechanical testing, including the discussion of magnesium yield and its assimilation rate.
EN
The study involved using the liquid-solid compound casting process to fabricate a lightweight ZE41/AlSi12 bimetallic material. ZE41 melt heated to 660 °C was poured onto a solid AlSi12 insert placed in a steel mold. The mold with the insert inside was preheated to 300 °C. The microstructure of the bonding zone between the alloys was examined using optical microscopy and scanning electron microscopy. The chemical composition was determined through linear and point analyses with an energy-dispersive X-ray spectroscope (EDS). The bonding zone between the magnesium and aluminum alloys was about 250 μm thick. The results indicate that the microstructure of the bonding zone changes throughout its thickness. The structural constituents of the bonding zone are: a thin layer of a solid solution of Al and Zn in Mg and particles of Mg-Zn-RE intermetallic phases (adjacent to the ZE41 alloy), a eutectic region (Mg17(Al,Zn)12 intermetallic phase and a solid solution of Al and Zn in Mg), a thin region containing fine, white particles, probably Al-RE intermetallic phases, a region with Mg2Si particles distributed over the eutectic matrix, and a region with Mg2Si particles distributed over the Mg-Al intermetallic phases matrix (adjacent to the AlSi12 alloy). The microstructural analysis performed in the length direction reveals that, for the process parameters tested, the bonding zone forming between the alloys was continuous. Low porosity was observed locally near the ZE41 alloy. The shear strength of the AZ91/AlSi17 joint varied from 51.3 to 56.1 MPa.
20
Content available remote Rheology-based approach of design the dieless drawing processes
EN
Dieless drawing process is based on local heating and simultaneously controlled stretching of the workpiece and allows elongation of the workpiece without using a deforming die. This process is usually used for deformation of wires, tubes and bars. The disadvantage of the dieless drawing process is the unevenness of the product diameter along its length. The present paper shows that unevenness can be substantially reduced by dividing the process into several stages. After each stage complete recrystallization of the material must be guaranteed for restoration of plasticity. The value of the strain in each stage must correspond to the area of intensive hardening on the stress–strain curve of the processed material. Thus, the proposed approach is based on the use of the special features of rheology properties of the material. The proposed approach was validated on the example of laser dieless drawing of magnesium alloy tubes.
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