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1
Content available remote Mechanical properties and structure of magnesium alloy AS31
EN
Contemporary materials should possess high mechanical properties, physical and chemical, as well as technological ones, to ensure long and reliable use. The non-ferrous metals alloys used nowadays, including the magnesium alloys, meet the above-mentioned requirements and expectations regarding the contemporary materials. Magnesium alloys are primarily used in aeronautical and automobile industry in wide variety of structural characteristics because of their favorable combination of tensile strength (160 to 365 MPa), elastic modulus (45 GPa), and low density (1 740 kg/m3), which is two-thirds that of aluminum). Magnesium alloys have high strength-to-weight ratio (tensile strength/density), comparable to those of other structural metals. [1-6] Knowledge of the relaxation properties of metal materials at high temperatures is necessary for the verification of susceptibility of castings to the creation of defects during the production process. Temperature limits of materials where highest tension values are generated may be detected with tensile tests under high temperatures. The generated tensions in the casting are a cause of the creation and development of defects. At acoustic emission (hereinafter called the "AE") use, tensile tests at high temperatures may, among other things, be used for analysis of the AE signal sources and set, in more detail, the temperature limit of elastic-plastic deformations existence in the material under examination. The results of the temperature drop where tension at casting cooling is generated or its release at heating are basic data for controlled cooling mode (and temperature of casting knocking out of the form) as well as necessary for the thermal mode for the casting tension reduction. [7-9] Knowledge of elastic-plastic properties at elevated temperatures is often important for complex evaluation of magnesium alloys. Objective of the work was focused on determination of changes of elastic-plastic properties of magnesium alloy AS31.
2
Content available remote Superplastic properties of magnesium alloys
EN
Purpose: The paper summarises results of experiments aimed at development of structure of modified Mg-Al-Zn alloys at hot deformation. Design/methodology/approach: methods ARB and ECAP were used in the described experiment. It was proved that hardly forming materials could achieve very high plastic properties. Findings: After making plastics deformation, the using materials of alloys AZ61 and AZ91 analysed superplastics behaviour, it was certified by obtaining results, when ductility to rupture of alloy AZ91 was 418%, it is demonstrated at conclusion of the article. Research limitations/implications: The experiment proved big influence of previous plastics deformation to ending values of mechanical properties. It was verified that better results are at rolling in more steps compared to rolling in one pass. Practical implications: The low submission temperature at last pass through die it causes obtaining higher final properties. Originality/value: It was obtained the material about grain size d dsim 0,7 micrometres during using the technology of ECAP. Abreast of it the technology ARB enabled to get material of grain size in interval d dsim 1-10 micrometres. The second technology brings higher strength properties. Only 3 cycles were sufficient to lower original grain size under limit 10 micrometres.
3
Content available remote Nickel super alloy INCONEL 713LC - structural characteristics after heat treatment
EN
Purpose: Nickel super alloy's products are mainly using for construction parts of jet engines, gas turbines and turbo-blowers. Design/methodology/approach: Super alloy was commercially produced and was investigated by using the light microscopy (OLYMPUS IX 71) and local chemical microanalysis and by the scanning electron microscopy (JEOL JSM 50A). Findings: we found a mode of optimum heat treatment. On the basis of obtained results it is possible to recommend a following regime of heat treatment: heating and dwell at the temperature exceeding 1240 degrees centigrade (min. 1260 degrees centigrade), so that precipitates at the grain boundaries dissolve completely, with subsequent slow cooling down to the temperature of approx. 940-950 degrees centigrade, so that there occurs intensive intra-granular precipitation of intermetallic phase gamma'. Research limitations/implications: The experiment was limited by occurrence a void in cast alloys. Practical implications: Nickel super alloy's products are mainly using for construction parts of jet engines, gas turbines and turbo-blowers. Originality/value: Mode of optimum heat treatment was proposed. On the basis of obtained results it is possible to recommend the most suitable heat treatment, which produce intensive intra-granular precipitation of intermetallic phase gamma'. It was received a new konw-how in this field.
4
Content available remote Mechanical properties of magnesium casting alloys
EN
Purpose: In the following paper there have been the properties of the MCMgA112Zn1, MCMgAl9Zn1, MCMgAl6Zn1, MCMgAl3Zn1 magnesium cast alloy as-cast state and after a heat treatment presented. Design/methodology/approach: A casting cycle of alloys has been carried out in an induction crucible furnace using a protective salt bath Flux 12 equipped with two ceramic filters at the melting temperature of 750 plmin 10 degrees centigrade, suitable for the manufactured material. The following results concern sliding friction, mechanical properties, scanning microscopy. Findings: The different heat treatment kinds employed contributed to the improvement of mechanical properties of the alloy with the slight reduction of its plastic properties. Research limitations/implications: According to the alloys characteristic, the applied cooling rate and alloy additions seems to be a good compromise for mechanical properties and microstructures, nevertheless further tests should be carried out in order to examine different cooling rates and parameters of solution treatment process and aging process. Practical implications: The concrete examples of the employment of castings from magnesium alloys in the automotive industry are elements of the suspension of the front and rear axes of cars, propeller shaft tunnel, pedals, dashboards, elements of seats, steering wheels, elements of timer-distributors, air filters, wheel bands, oil sumps, elements and housings of the gearbox, framing of doors and sunroofs, and others, etc. Originality/value: Contemporary materials should possess high mechanical properties, physical and chemical, as well as technological ones, to ensure long and reliable use. The above mentioned requirements and expectations regarding the contemporary materials are met by the non-ferrous metals alloys used nowadays, including the magnesium alloys.
5
Content available remote Heat treatment impact on the structure of die-cast magnesium alloys
EN
Purpose: In the following paper there have been the structure and properties of the MCMgAl6Zn1 magnesium cast alloy as-cast state and after heat treatment presented. Design/methodology/approach: A casting cycle of alloys has been carried out in an introduction crucible furnace using a protective salt bath Flux 12 equipped with two ceramic filters at the melting temperature of 750 plmin 10 degrees centigrade, suitable for the manufactured material. The following results concern light and scanning microscopy, X-ray qualitative and quantitative microanalysis. Findings: The results of the EDS chemical composition analysis confirm the presence of magnesium, aluminium, manganese, and zinc, constituting the structure of alpha solid solution with Mg17Al12 placed mainly on the grain order in the form of plates, also the phase AlMnFe with irregular shape, occurred often in the shape of blocks or needles and the Laves phase Mg2Si. Research limitations/implications: According to the alloys characteristics, the applied cooling rate and alloy additions seems to be good compromise for mechanical properties and microstructures, nevertheless further tests should be carried out in order to examine different cooling rates and parameters of solution treatment process and aging process. Practical implications: A desire to create as light vehicle constructions as possible and connected with it low fuel consumption have made it possible to make use of magnesium alloys as a constructional material in automotive industry. Originality/value: The undertaken examinations aim at defining the influence of a chemical composition and precipitation processes on the structure and casting magnesium alloy properties in its as-cast state and after heat treatment with a different content of alloy components.
6
Content available remote Fracture analysis of selected magnesium alloys after different testing methods
EN
Purpose: of this paper is to extend a complex evaluation of magnesium alloys which requires very often knowledge mechanical properties. These properties are connected with microstructure that is influenced by metallurgical and technological factors and conditions of exploitation. Very important information for design and exploitation of these alloys is knowledge of fracture characteristics. Design/methodology/approach: Testing methods used magnesium alloys were based on tensile test and torsion test. The methods of the light microscopy and SEM for metallographic and fracture analyses of alloys after testing were used. Findings: Objective of this work consisted in determination of changes of mechanical properties and fracture characteristics of magnesium alloy in dependence on testing methods. Mg-Al alloy with graduate aluminium content as cast state and after heat treatment was used. It was confirmed that during heating at chosen temperatures there occurs partial dissolution of minority phases. Research limitations/implications: According to the alloys characteristic, the applied cooling rate and alloy additions seems to be a good compromise for mechanical properties and microstructures, nevertheless further tests should be carried out in order to examine different cooling rates and parameters of solution treatment process and aging process. Practical implications: The results may be utilized for a relation between plastic and strength properties of the investigated material in process of research and manufacturing. Originality/value: These results contribute to complex evaluation of properties magnesium alloys namely for explanation of fracture mechanism in changing condition of testing and exploitation. The results of this paper are determined for research workers deal by development new exploitations of magnesium alloys.
7
Content available remote Forging and rolling of magnesium alloy AZ61
EN
Purpose: The paper summarises results of experiments aimed at development of structure of modified alloy AZ61 at hot deformation. Design/methodology/approach: Deformation behaviour of alloy was verified at the temperature of 420 degrees centigrade by rolling at 380 degrees centigrade by forging, respectively. Findings: Magnesium alloy AZ 61 have hexagonal structure and their forming is at room temperatures very difficult, that's why big plastic deformations are carried out in hot condition. After plastic deformations was obtained that original grain size decreased 15 times. Research limitations/implications: This paper provide data about magnitude of deformation, strain rate and temperature of forming at different techniques of plastic deformation. It was aimed to determine the conditions for non problem rolling and forging respectively. Practical implications: Initial structure was as cast and after heat treatment T4. Heat treatment appeared much better for forming as well as forging than rolling because of state of stress. Originality/value: Role of beta phase (Mg17Al12) in these alloys at plastic forming is very important, such that how it was obtained, best final properties of AZ 61 alloy supports very fine particles, distributed into Mg matrix. Next a relevant information is that multi stage forming process is much better in comparison with a big single reduction.
8
Content available remote Microstructure of MCMgAl12Zn1 magnesium alloy
EN
In this paper is presented the structure of the cast magnesium alloys as cast state and after heat treatment cooled with different cooling rate, depending on the cooling medium (furnace, water, air). For investigations samples in shape of 250x150x25 mm plates were used. The structure have been study in the light microscope, scanning electron microscope equipped with an electron back scattering facility. The effects of the addition of Al on the microstructure were also studied. In the analysed alloys a structure of [alpha] solid solution and fragile phase [beta] (Mg_17Al_12) occurred mainly on grain borders as well as eutectic and phase with Mn, Fe and Si. Investigation are carried out for the reason of chemical composition influence and precipitation processes influence to the structure and mechanical properties of the magnesium cast alloys with different chemical composition in as cast alloys and after heat treatment.
10
Content available remote Mikrostruktura odlewniczych stopów magnezu Mg - Al
PL
W pracy przedstawiono strukturę odlewniczego stopu magnezu MCMgAl9Zn1 w stanie odlanym i po obróbce cieplnej. Zaprezentowane wyniki dotyczą mikroskopii świetlnej i skaningowej, rentgenowskiej analizy fazowej jakościowej, mikroanalizy rentgenowskiej jakościowej i ilościowej. Podejmowane badania, mają na celu określenie wpływu składu chemicznego i procesów wydzieleniowych na strukturę odlewniczych stopów magnezu.
EN
In the following paper there have been the structure of the MCMgAl9Zn1 magnesium cast alloy as-cast state and after a heat treatment presented. The following results concern light and scanning microscopy, quantitative X-ray diffraction method, X-ray qualitative and quantitative microanalysis.
11
Content available remote Mikrostruktura i własności mechaniczne odlewniczych stopów magnezu Mg-Al
PL
W pracy przedstawiono strukturę i właściwości odlewniczego stopu magnezu MCMgAl6Zn1 w stanie odlanym i po obróbce cieplnej. Zaprezentowane wyniki dotyczą mikroskopii świetlnej, analizy rozkładu powierzchniowego pierwiastków, obserwacji powierzchni na przełomach porzecznych odlewniczych stopów magnezu i prób wytrzymałościowych w temperaturze pokojowej.
EN
In the following paper there have been the structure and properties of the MCMgAl6Zn1 magnesium cast alloy as-cast state and after a heat treatment presented. The following results concern light microscopy, quantitative X-ray diffraction method, The observed fractures in the casting magnesium alloys and tensil test in the room temperature.
12
Content available remote Structural evolution of cooper during by several plastic deformation
EN
Some experimental results describing microstructural evolution in commercially pure cooper during several plastic deformations by equal channel angular pressing (ECAP) are present. The die angle used in ECAP determines both the shear plane orientation and the strain per pas. It is interesting to study the effect of the separate shear plane orientation and the strain per pass on microstructural development. Authors have experimentally determined development of copper structure and properties at ECAP. Mechanisms of ultrafine grain formation are discussed.
13
Content available remote Microstructural behaviour of AZ91D magnesium alloy during heat treatment
EN
Magnesium alloys are often applied in different spheres of life, including the aircraft and motor vehicle as well as metallurgical, chemical and electrical-chemical industries. Magnesium alloys are grouped in two alloy families: Mg-Al alloys and Mg-Zr alloys. Mg-Al-Zn alloys are the most commonly used magnesium alloys for structural components. AZ91D alloy is a widely used casting magnesium alloy. The microstructure behaviour of AZ91D alloy after heat treatment has been investigated. The casting temperature was 740°C and solution treatment was performed at 415°C/1÷48h/air with aging at 165°C/4÷48h/air. AZ91D alloy is constitiuted with the following phases: - alpha phase - solid solution of Al in Mg; - beta phase (Mg17Al12) - continuous on the grain boundary and discontinuous in (alpha+beta) areas; - intermetallic phases -> Mg2Si, MnAl, MnAl4. The research methodology covered microscopic investigation as well as LM, SEM and energy dispersive X-ray (EDX) analysis.
PL
Stopy magnezu znajdują coraz większe zastosowanie w różnych dziedzinach życia, w tym głównie w przemyśle lotniczym i samochodowym, a także metalurgicznym, chemicznym i elektrochemicznym. Stopy magnezu można podzielić na dwie grupy: stopy Mg-Al oraz stopy Mg-Zr. Stopy Mg-Al-Zn są najczęściej stosowanymi stopami magnezu na elementy konstrukcyjne. Największe zastosowanie znalazł odlewniczy stop AZ91D. Przeprowadzone badania dotyczyły określenia zmian mikrostruktury stopu AZ91D po obróbce cieplnej. Temperatura odlewania wynosiła 740°C, przesycanie prowadzono w temperaturze 415°C/1÷48h/powietrze z następnym starzeniem w temperaturze 165°C/4÷48h/powietrze. Stop AZ91D po odlaniu charakteryzuje się strukturą złożoną z następujących faz: - faza alfa - roztwór stały Al w Mg; - faza beta (Mg17Al12) - wydzielenia ciągłe na granicach ziarn oraz nieciągłe w obszarach (alfa+beta); - fazy międzymetaliczne -> Mg2Si, MnAl, MnAl4. Metodyka badawcza obejmowała badania mikrostruktury z wykorzystaniem mikroskopii świetlnej i skaningowej oraz mikroanalizy składu chemicznego.
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