Ograniczanie wyników
Czasopisma help
Autorzy help
Lata help
Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 237

Liczba wyników na stronie
first rewind previous Strona / 12 next fast forward last
Wyniki wyszukiwania
Wyszukiwano:
w słowach kluczowych:  magnesium alloys
help Sortuj według:

help Ogranicz wyniki do:
first rewind previous Strona / 12 next fast forward last
EN
Ultrasonic assisted active-passive filling friction stir repairing (A-PFFSR) was proposed to repair volume defects in the metallic parts. Sound joints without interfacial defects could be achieved. Firstly, the ultrasonic was beneficial to improving material flow and atom diffusion, and then eliminated kissing bond defects compared to conventional A-PFFSR joints. Secondly, the equiaxed grains were refined by ultrasonic vibration. Lastly, the repairing passes were reduced due to the ultrasonic, which decreased softening degree of the repaired joints. The maximum tensile strength of 150 MPa was achieved. Therefore, this strategy to repair the volume defects is feasibility and potential in the remanufacturing fields of aerospace and transportation.
2
Content available remote Galwaniczne powłoki niklowe na stopach magnezu
PL
W pracy przedstawiono wyniki badań wytwarzania kompozytowych powłok niklowych zbrojonych cząstkami węglika krzemu o wielkości nanometrycznej. Powłoki osadzano elektrolitycznie na podwarstwie Ni-P z kąpieli typu Wattsa z dodatkami substancji organicznych. Przedstawiono mikrostruktury uzyskanych powłok, wyniki badań korozyjnych oraz badań przyczepności powłok metodą udaru cieplnego.
EN
The paper presents the results of the studies of electrodeposited composite nickel coatings reinforced with nanometer-size silicon carbide particles. The coatings have been deposited on the Ni-P sublayer in Watts-type solution with organic additives. The microstructure of the coatings, as well as the results of corrosion tests and coating adhesion tested with the method of the heat shock have been also presented.
EN
The paper presents the results of tests concerning the effect of the extrusion process in the complex strain state on the microstructure and properties of one of magnesium alloy with aluminium, zinc and manganese, designated AZ61. Due to its specific gravity, it is increasingly being used in the automotive and aerospace industries to reduce the weight of structural elements. As a result of plastic deformation processes, rods with a diameter of 8, 6 and 4 mm were obtained from AZ61 magnesium alloy. The microstructure analysis was performed using light and electron microscopy (STEM) techniques in the initial state and afterplastic deformation. Microstructure studies were supplemented with a quantitative analysis using the Metilo program. A number of stereological parameters were determined: average diameter of grain, shape factor. A static tensile test was carried out at 250ºC and 300ºC, at deformation rates of 0.01, 0.001 and 0.0001 m·s-1. Better plastic properties after deformation using KoBo methodwere obtained than with conventional extrusion.
EN
A numerical analysis of the process of single-pass rolling of AZ31 magnesium alloy bars in the three-high skew rolling mill has been carried out in the study. Based on the obtained investigation results, the effect of rolling speed on the band twist and the state of stress and strain occurring in the rolled band has been determined. From the obtained results of the numerical studies it has been found that with the increase in rolling speed the unit band twist angle θ, increase, which translates into an increase in the value of tangential stress in the axial zone of the rolled bar. This contributes directly to an increase in redundant strain in the rolled bar axial zone, which brings about a structure refinement. To verify the effect of rolling speed on the flow pattern and the stress and strain state, experimental tests were carried out. It has been found from the tests that the band twist (flow pattern) contributes to obtaining a bimodal structure in the bar cross-section.
5
EN
Selective Laser Melting (SLM) of magnesium alloys is the technology undergoing dynamic development in many research centres. The results are promising and make it possible to manufacture defect-free material with better properties than those offered by the manufacturing technologies used to date. This review aims to evaluate present state as well as main challenges of using Laser Powder Bed Fusion (L-PBF) for processing magnesium alloys as an alternative way to conventional technolo-gies to manufacture parts in the aerospace industry. This literature review is the first one to outline information concerning the potential to use magnesium alloys in the aerospace industry as well as to summarise the results of magnesium alloy pro-cessing using AM technologies, in particular L-PBF. The available literature was reviewed to gather information about: the use of magnesium alloys in the aerospace industry-the benefits and limitations of using magnesium and its alloys, examples of applications using new processing methods to manufacture aerospace parts, the benefits and potential of using L-PBF to process metallic materials, examples of the use of L-PBF to manufacture aerospace parts, and state-of-the-art research into L-PBF processing of magnesium and magnesium alloys.
6
Content available remote The microstructure and creep properties of as-cast Mg-Sn-Si-(Al) magnesium alloys
EN
Magnesium alloys containing rare earth metals exhibit good creep resistance up to 300 °C and good tensile properties at ambient temperature. The high cost of rare earth has led to studies regarding the creep resistance of Mg alloys with cheap alloying elements (Sn, Ca, Si) that could be substituted for Mg-RE alloys. In this paper, the influence of Si and Al on microstructure and mechanical properties of Mg-7Sn alloy was investigated using optical (LM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction analysis (XRD), tensile tests and creep tests at 200–250 °C. Microstructure of as-cast alloys consists of α-Mg matrix and intermetallic compounds at the interdendritic regions. Heat treatment consisting of solid solution treatment and ageing increases the tensile properties at ambient temperature due to the precipitation of the fine Mg2Sn phase. The creep resistance of aged Mg-7Sn alloy is poor. The addition of Si and Al to Mg-7Sn alloy has resulted in improving the creep resistance due to the refinement of Mg2Sn phase and the appearance of Mg2Si phase at the grain boundaries. The Mg-7Sn-1Si alloy exhibits better creep resistance at 200 °C than Mg-7Sn-5Si and Mg-7Sn-5Si-2Al alloys. The Mg-7Sn alloys with 5% Si have better creep properties at 250 °C in comparison to Mg-7Sn-1Si alloy.
EN
The paper explores the new method of improving the workability of materials in the dieless drawing processes. The proposed method is based on the implementation of a multi-pass incremental deformation. Moreover, in each pass, strain and strain rate sensitivity of flow stress should be positive and significant. An approach based on the finite element calculation of instability coefficient of plastic deformation and simultaneous modeling of material ductility were applied for prediction of the workability. Two dieless drawing processes have been investigated. The difference was related to the heating system-induction heating and laser heating. FE simulations and experimental tests for three materials, two magnesium alloys (MgCa0.8 and MgNi19) and pure copper were performed. It was shown that the most effective increase in workability by multi-pass deformation can be achieved using laser dieless drawing. This is possible due to the shorter heating area and, as a consequence, the larger strain rate, which leads to better stability of the deformation process.
EN
The research is focused on the study of the temperature dependence of the internal damping of selected magnesium alloys with different contents of aluminium - AZ31 and AZ61. These alloys are currently widely used in various types of industry, mainly in the automotive industry. It belongs to a group of materials called HIDAMETS because they have excellent damping properties. The internal damping of the samples was measured on a unique ultrasonic device constructed at Žilina University in Žilina. Specimens were measured at baseline in the temperature range from 25 °C to 400 °C. Changes in internal damping caused by varying aluminium contents in investigated alloys were noted. As the aluminium content increases, maximum internal damping is achieved due to the formation, growth and subsequent dissolution of the continuous precipitate in the microstructure.
9
Content available Hybrydowa technologia HPDC&HSC
PL
W artykule przedstawiono rys historyczny oraz stan obecny technologii odlewania z wykorzystaniem ciśnienia zewnętrznego na przykładzie odlewania pod wysokim ciśnieniem (High Pressure Die Casting – HPDC) oraz prasowania w stanie ciekłym (Squeeze Casting – SC). Wykazano podobieństwa i różnice obu technologii oraz obszary wspólne, które zostały wykorzystane do budowy współczesnych, hybrydowych maszyn łączących cechy HPDC i SC. Ostatnie lata przyniosły rozwój konstrukcji maszyn ciśnieniowych, które umożliwiły hybrydyzację technologii z wysoką elastycznością procesu, polegającą na wyborze takiego sposobu przyłożenia ciśnienia zewnętrznego, w którym można pełniej wykorzystać jego wpływ jako czynnika termodynamicznego. Zaprezentowano doświadczenia w zakresie prasowania w stanie ciekłym i stało-ciekłym, uzyskane w badaniach prowadzonych w Instytucie Odlewnictwa w Krakowie.
EN
The article presents the history and current state of the technology of external pressure casting in the case of High Pressure Die Casting (HPDC) and Squeeze Casting (SC). The similarities and differences between the two technologies and the common areas that were used in the construction of modern hybrid machines combining the features of HPDC and SC were shown. Recent years have seen the development of pressure machine designs that have enabled the hybridisation of technologies with high flexibility of the process, consisting in the choice of such a method of applying external pressure in which its influence can be more effectively used as a thermodynamic factor. The following experiments were presented in the field of liquid and solid-liquid casting, obtained from research conducted at the Foundry Research Institute in Kraków.
EN
The artificial neural network method (ANN) is widely used in both modeling and optimization of manufacturing processes. Determination of optimum processing parameters plays a key role as far as both cost and time are concerned within the manufacturing sector. The burnishing process is simple, easy and cost-effective, and thus it is more common to replace other surface finishing processes in the manufacturing sector. This study investigates the effect of burnishing parameters such as the number of passes, burnishing force, burnishing speed and feed rate on the surface roughness and microhardness of an AZ91D magnesium alloy using different artificial neural network models (i.e. the function fitting neural network (FITNET), generalized regression neural network (GRNN), cascade-forward neural network (CFNN) and feed-forward neural network (FFNN). A total of 1440 different estimates were made by means of ANN methods using different parameters. The best average performance results for surface roughness and microhardness are obtained by the FITNET model (i.e. mean square error (MSE): 0.00060608, mean absolute error (MAE): 0.01556013, multiple correlation coefficient (R): 0.99944545), using the Bayesian regularization process (trainbr)). The FITNET model is followed by the FFNN (i.e. MAE: 0.01707086, MSE: 0.00072907, R: 0.99932069) and CFNN (i.e. MAE: 0.01759166, MSE: 0.00080154, R: 0.99924845) models with very small differences, respectively. The GRNN model has noted worse estimation results (i.e. MSE: 0.00198232, MAE: 0.02973829, R: 0.99900783) as compared with the other models. As a result, MSE, MAE and R values show that it is possible to predict the surface roughness and microhardness results of the burnishing process with high accuracy using ANN models.
EN
In this paper is discussed the effect of the inoculant mischmetal addition on the microstructure of the magnesium alloy AZ91. The concentration of the inoculant was increased in the samples within the range from 0.1% up to 0.6%. The thermal process was performed with the use of Derivative and Thermal Analysis (DTA). A particular attention was paid to finding the optimal amount of the inoculant, which causes fragmentation of the microstructure. The concentration of each element was verified with use of a spark spectrometer. In addition, the microstructures of every samples were examined with the use of an optical microscope and also was performed an image analysis with a statistical analysis using the NIS - Elements program. The point of those analyses was to examine the differences in the grain diameters of phase αMg and eutectic αMg+γ(Mg17Al12) in the prepared samples as well as the average size of each type of grain by way of measuring their perimeters. This paper is the second part of the introduction into a bigger research on grain refinement of magnesium alloys, especially AZ91. Another purpose of this research is to achieve better microstructure fragmentation of magnesium alloys without the relevant changes of the chemical composition, which should improve the mechanical properties.
EN
This work presents the results of the research of the effect of the inoculant Emgesal Flux 5 on the microstructure of the magnesium alloy AZ91. The concentration of the inoculant was increased in samples in the range from 0.1% to 0.6%. The thermal processes were examined with the use of Derivative and Thermal Analysis (DTA). During the examination, the DTA samplers were preheated up to 180 °C. A particular attention was paid to finding the optimum amount of inoculant, which would cause fragmentation of the microstructure. The concentration of each element was verified by means of a spark spectrometer. In addition, the microstructures of the samples were examined with the use of an optical microscope, and an image analysis with a statistical analysis using the NIS-Elements program were carried out. Those analyses aimed at examining the differences between the grain diameters of phase αMg and eutectic αMg+γ(Mg17Al12) in the prepared samples as well as the average size of each type of grain by way of measuring their perimeters. This paper is an introduction to a further research of grain refinement in magnesium alloys, especially AZ91. Another purpose of this research is to achieve better micro-structure fragmentation of magnesium alloys without the related changes of the chemical composition, which should improve the mechanical properties.
13
Content available Surface Quality in Milling of AZ91D Magnesium Alloy
EN
This paper is an attempt at determining the effect of technological parameters of milling on the surface roughness of the AZ91D magnesium alloy. The cutting tool used in tests was a TiAlN-coated carbide milling cutter. The milling tests were carried out at variable cutting speed, feed per tooth and depth of cut, and the results were compared. The analysis was based on the 2D roughness parameters measured on the end and lateral faces of specimens, as well as on the 3D roughness parameters measured on the end faces of specimens. The test results indicated that the increase in the feed per tooth results in the increase in the value of 2D and 3D surface roughness parameters. It was found that cutting speed and axial depth of cut have a negligible effect on the 2D roughness of the workpiece surface, whereas the increase in cutting speed results in the reduction of the 3D surface roughness parameters.
14
Content available remote Galwaniczne powłoki niklowe na stopach magnezu
PL
W pracy przedstawiono wyniki badań wytwarzania kompozytowych powłok niklowych zbrojonych cząstkami węglika krzemu o wielkości nanometrycznej. Powłoki osadzano elektrolitycznie na podwarstwie Ni-P z kąpieli typu Wattsa z dodatkami substancji organicznych. Przedstawiono mikrostruktury uzyskanych powłok, wyniki badań korozyjnych oraz badań przyczepności powłok metodą udaru cieplnego.
EN
The paper presents the results of the studies of electrodeposited composite nickel coatings reinforced with nanometer-size silicon carbide particles. The coatings have been deposited on the Ni-P sublayer in Watts-type solution with organic additives. The microstructure of the coatings, as well as the results of corrosion tests and coating adhesion tested with the method of the heat shock have been also presented.
PL
Przedstawiono zakres wymagań wobec powierzchni szlifowanych pod nakładanie warstw przeciwzużyciowych PVD w odniesieniu do stopów magnezu. Omówiono trudności z tym związane oraz doniesienia literaturowe. Opisano rozwiązania stosowane w przypadku szlifowania magnezu ściernicami konwencjonalnymi ze spoiwem ceramicznym z wykorzystaniem czyszczenia czynnej powierzchni ściernic w trakcie szlifowania. Ustalono parametry procesów obróbki oraz dokonano oceny struktury geometrycznej powierzchni, mierząc chropowatość w układzie 3D.
EN
In the paper the range of requirements concerning grinded surface layers for deposition of protective PVD coatings on magnesium alloys has been presented. Also difficulties concerning the preparation of surface layer and literature review have been depicted. For solving of the problems concerning proper preparation of magnesium alloy surface layer the conventional grinding process using ceramic grinding wheels and the process of cleaning of CSGW during machining has been applied. The machining parameters has been determined and the surface geometrical structure has been assessed using optical profiling in 3D configuration.
16
EN
Wire saw technology is a method that works great in industrial applications - it is a dominant method in the production of silicon wafers. But almost all kinds of brittle materials (ceramics, rocks, meteorite and minerals or wood) can be cut using wire saw. Question, this article will try to answer is whether this is also applicable to magnesion alloys? Article presents selected problems from an area of abrasive treatment of magnesium alloys. This includes effects of research, concerning possibilities of application of abrasive diamond wire in the process of cutting magnesium alloys AM60 and AZ91 as well as results concerning surface quality obtained after cutting with the abrasive diamond wire German Company HK Präzisionstechnik.
EN
The article presents tests results of the influence of deformation methods on the microstructure and properties of alloy WE43. There were direct extrusion tests and extrusion with KoBo method performed. An assessment of the influence of the methods of deformation on the microstructure and the mechanical properties of the achieved rods from alloy WE43 was conducted. There was an analysis of microstructure carried out with the use of light and scanning microscopy techniques in the initial state and after plastic deformation. Static tensile test was conducted in temperature of 350°C at a speed of 0.0001 m·s-1 and microhardness measurements were performed of HV0.2. On the basis of the achieved mechanical tests results it was stated that in the temperature of 350°C for samples deformed with the use of KoBo method there was an effect of superplastic flow found. The value of elongation achieved was 250% which was 3 times higher than in case of classic extrusion (80%).
EN
The influence of polysaccharide chitosan coatings on the corrosion resistance of magnesium alloys Mg1Ca, Mg1Ca1Si and Mg4Zn1Ca is studied in 0.1 M sodium sulphate solution. It has been shown that localized corrosion of all magnesium alloys proceeds along grain boundaries and around precipitates. After long-term immersion of magnesium alloys (Mg1Ca and Mg4Zn1Ca) metallic ions are detected in the solution. The chitosan and chitosan/TiO2 composite coatings accelerate corrosion of Mg1Ca, Mg1Ca1Si and Mg4Zn1Ca in sodium sulphate based solutions.
PL
Badano wpływ polisacharydowych chitozanowych powłok na odporność korozyjną stopów magnezu typu Mg1Ca , Mg1Ca1Si i Mg4Zn1Ca w 0,1 M roztworze siarczanu VI sodu (Na2SO4). Korozja tych stopów przebiega wzdłuż granic ziaren i wokół wydzieleń. Po kilkudziesięciu godzinach ekspozycji stopów w roztworze elektrolitu jony metali były obecne w roztworze w przypadku stopów Mg1Ca i Mg4Zn1Ca. Obecność powłok chitozanowych i powłok chitozanowych zawierających TiO2 powodowała przyspieszenie korozji stopów magnezu w roztworze siarczanu VI sodu.
PL
Praca dotyczy badań właściwości mechanicznych jednego ze stopów magnezu, który ze względu na jego mały ciężar właściwy jest coraz częściej wykorzystywany w przemyśle motoryzacyjnym, w celu obniżenia masy elementów konstrukcyjnych pojazdów. Omawiany w pracy materiał to stop magnezu z aluminium, cynkiem i manganem o nazwie handlowej AZ31B. Chociaż stop ten jest bardzo atrakcyjny ze względu na jego małą gęstość (możliwość wykorzystania w konstrukcjach lekkich), to kształtowanie z niego elementów nadwozi samochodowych jest znacznie utrudnione przez jego niską odkształcalność w temperaturze otoczenia. W celu wytwarzania bardziej skomplikowanych wyrobów ze stopu magnezu AZ31B wymagane jest jego podgrzanie. Chcąc zastąpić dany element stalowy elementem z tego stopu, należy również pamiętać, że stop AZ31B charakteryzuje się niższym modułem sprężystości podłużnej niż stal (mniejsza sztywność). Praca przedstawia wyniki badań wpływu temperatury oraz prędkości odkształcania na przebieg naprężeń uplastyczniających dla blach z tego stopu. W pracy opisano stanowisko badawcze i metodologię przeprowadzania prób jednoosiowego rozciągania. Badania przeprowadzono przy 2 prędkościach odkształ- cania, w 5 temperaturach 21, 100, 200, 300 oraz 350°C. Wyznaczono parametry wytrzymałościowe takie, jak: umowna granica plastyczności, moduł Younga, naprężenie maksymalne i wydłużenie w momencie zerwania. Wykazano, że wraz ze wzrostem temperatury poziom naprężeń uplastyczniających maleje, a wydłużenie całkowite przed zerwaniem wyraźnie rośnie; poprawiają się tym samym właściwości plastyczne badanego stopu magnezu.
EN
This paper concerns testing of the mechanical properties of a certain magnesium alloy, which, due to its specific gravity, is being used with increasing frequency in the motorization industry to reduce the weight of vehicles’ structural elements. The material discussed in this paper is a magnesium alloy with aluminum, zinc and manganese, sold under trade name AZ31B. Although this alloy is very attractive considering its low density (possibility of using it in light constructions), forming body elements out of it poses significant difficulties due to its low deformability at ambient temperature. In order to manufacture more complicated products from AZ31B magnesium alloy, it must be heated. When replacing a given steel element with an element made of this alloy, one must also remember that AZ31B alloy is characterized by a lower Young’s modulus than steel (lower rigidity). This paper presents the results of tests of the effect of temperature and strain rate on the progression of flow stresses in sheets made from this alloy. The test stand and methodology of conducting uniaxial tensile tests are described. Tests were conducted at 2 strain rates, at 5 temperatures: 21, 100, 200, 300 and 350°C. The following strength parameters were determined: offset yield strength, Young’s modulus, maximum stress and elongation upon breaking. It was demonstrated that the level of flow stresses decreases as temperature increases, and total elongation prior to breaking clearly increases, thus improving the plastic properties of the studied magnesium alloy.
PL
Procesy oparte na łączeniu materiałów w stanie stałym stanowią skuteczne rozwiązanie pod względem aspektów wytrzymałościowych i trwałości wykonanego elementu. W ostatnich latach nastąpiło duże zainteresowanie środowisk naukowo-badawczych i przemysłu rozwijaniem niekonwencjonalnych metod łączenia materiałów konstrukcyjnych w przemyśle transportowym, w tym metodami zgrzewania tarciowego z przemieszaniem FSW (Friction Stir Welding). W pracy przedstawiono charakterystykę procesu FSW na podstawie złączy cienkich blach metalicznych stopów Al Mg i czystego technicznie tytanu GRADE 3 (AMS-T-9046 / AMS 4900) grubości 0,4 i 0,5 mm. Analizując omawiane właściwości połączeń oraz modyfikacje metalurgiczne strefy złączą, poprzez wpływ głównych zmiennych procesowych, co ma wpływ na jakość złączy FSW. Proces zgrzewania zrealizowano na 3 osiowej pionowej frezarce sterowanej numerycznie, wyposażonej w specjalnie przygotowany uchwyt mocujący, z wykorzystaniem narzędzi z węglika wolframu oraz ceramiki narzędziowej. Parametry geometryczne dostosowano do grubości blachy na podstawnie algorytmu wg danych literaturowych [12]. Podczas procesu realizowano pomiar sił osiowych i promieniowych, wykorzystując precyzyjny siłomierz piezoelektryczny, w celu analizy efektu uplastycznienia łączonych blach. Wytrzymałość połączeń FSW wyznaczono na podstawie statycznej próby rozciągania w temperaturze pokojowej. Na tej podstawie zdefiniowano efektywność złącza w porównaniu do materiału rodzimego. Wykazano, że metoda FSW pozwala na wykonywanie wysokiej jakości wolnych od wad zgrzein cienkich blach metalicznych, zarówno z metali nieżelaznych, jak i z czystego technicznie tytanu GRADE 3 (AMS-T-9046 / AMS 4900). Efektywność wykonanych połączeń FSW znacznie przekraczała 80% wytrzymałości na rozciąganie materiału rodzimego. Wykazano, że proces FSW może stanowić alternatywę dla procesu spawania łukowego, nitowania lub zgrzewania oporowego RSW.
EN
Processes based on a joining of materials in the solid state, constitute an effective solution to the aspects of strength and durability of the produced element. In recent years there has been a great interest of research and industry to develop unconventional methods of joining construction materials in the transport industry, including Friction Stir Welding. This paper presents the characteristics of the FSW process based on the joints of thin sheet of Al and Mg alloys and technically pure GRADE 3 titanium (AMS-T-9046 / AMS 4900) of 0.4 and 0.5 mm in thicknesses. Analyzing the joints properties and metallurgical modifications through the influence of the main process variables, which affects the quality of the FSW joints. The welding process was carried out on a 3 axial vertical numerically controlled milling machine, equipped with a specially prepared fixing device, using tungsten carbide tools and ceramics tool. Geometric parameters were adjusted to the thickness of the sheet using the algorithm according to literature [12]. During the process, axial and radial forces were measured using a precision piezoelectric dynamometer to analyze the effect of the plasticization in the joined area. The ultimate tensile strength (UTS) of FSW joints was determined by the static tensile test at room temperature. On this basis, the efficiency of the joint was determined as compared to the parent material (PM). It has been shown that the FSW method allows for the production of high quality defect free joints both from nonferrous metals as well as from pure GRADE 3 titanium (AMS-T-9046 / AMS 4900). Efficiency of FSW connections exceeds 80% of the tensile strength of parent material. It has been shown that the FSW process can be an alternative for arc welding, riveting or RSW welding.
first rewind previous Strona / 12 next fast forward last
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.