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Analysis of the structure Hadfield steel depending on the load deformation
Darida, Jiří ; Julišová, Martina (referee) ; Klakurková, Lenka (advisor)
This bachelor´s thesis deals with the analysis of the structure Hadfield steel depending on the load deformation. The first part of the thesis determines summary of basic mechanical and physical properties of Hadfield steel, its chemical composition, the influence of alloying elements on the resulting microstructure, manufacturing, heat treatment, hardening mechanisms and its use in technical applications. Attention is also paid to the various types of work hardening among which include explosive strengthening. The experimental part of the thesis is focused on the analysis of samples Hadfield steel, which were stressed by different loading conditions. Analysis of these samples consists of observations of structural changes and measurement of work hardening using microhardness in surface and sub-surface region of the sample. The final part presents the view into the future and overall evaluation of results.
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Manufacturing Process and Applications of Composite Materials for buses parts
Rusek, Jan ; Julišová, Martina (referee) ; Němec, Karel (advisor)
The aim of the bachelor’s thesis is the evaluation and demonstration of the usability of composite materials in the bus industry. The first chapter provides an overview of selected types of composite materials, basic classification, description of their parts and demonstrations of methods of production. The second part of the bachelor’s thesis is focused on the evaluation of the advantages and disadvantages of using composite materials. The last part is focused on the producion of the sample from fiberglass.
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Mechanical properties and structure of the aluminum alloy after heat treatment
Roleček, Jakub ; Julišová, Martina (referee) ; Juliš, Martin (advisor)
The presented bachelor´s thesis deals with the influence of heat treatment especially artificial aging on mechanical and structural properties of AlSi7Mg0.6 alloy. Cylindrical test bars of diameter 6 mm and 9 mm cast into a self-supporting ceramic shell made by plaster investment technology were used as experimental samples. These test bars were cast by Alucast whereas the patented technology of casting- JF casting was used. On the test bars was carried out the T6 heat treatment according to the Standards AMS 2771C. After the solution annealing were test bars divided to the six groups and put through various time of artificial aging, namely from 2 to the 12 hours. In order to evaluate the effect of the time of artificial aging on the structure and mechanical properties of both diameters of the test bars, the method of light microscopy, Brinell hardness test and static traction test were used. Also SDAS quantification was carried out by means of image analysis. On the grounds results of experiments it is possible to state, that the best values of mechanical properties of both diameters of the cylindrical test bars were reached after 10 hours of artificial aging.
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Influence of AlCr Layer to Fatiague Properties of Nickel Superalloy IN 713LC at the Temperature 800°C
Šulák, Ivo ; Julišová, Martina (referee) ; Podrábský, Tomáš (advisor)
The present diploma thesis is focused on the effect of AlCr layer on the low cycle fatigue behaviour of cast polycrystalline superalloy IN713LC at 800°C. Protective layer is made by chemical vapour deposition followed by heat treatment. Fatigue tests were conducted in strain control mode with constant total strain amplitude and strain rate. The fatigue behaviour is assessed by cyclic hardening/softening curves, cyclic stress-strain curves, Manson-Coffin curves and Basquin curves. Microstructure was observed in as-received state and also after cyclic loading by means of optical microscopy and SEM.
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Anodizing of Aluminium and Its Alloys
Remešová, Michaela ; Julišová, Martina (referee) ; Čelko, Ladislav (advisor)
This thesis focuses on the hard anodic oxidation of aluminum and its alloys. As an experimental materials were used various aluminum materials, produced by cold forming and casting. The work contains information about chemical composition of the base materials, photographs of their microstructure, the results of surface roughness before and after anodic oxidation, photo anodized layer, measurements hardness oxide layers. For study were used methods light microscopy, scanning electron microscopy, surface profilometry and microhardness measurements.
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Optimisation of heat treatment of aluminium alloy AlSi7Mg0,6
Julišová, Martina ; Klakurková, Lenka (referee) ; Juliš, Martin (advisor)
The presented diploma thesis deals with various types of quenching and their respective effects on mechanical and structural properties of AlSi7Mg0.6 alloy castings. Cast with precision casting technology into a self-supporting ceramic shell made by plaster investment technology, flat test bars cast by Alucast were used as experimental samples. Sample castings were used in both cast state and after T6 heat treatment. Air-flow and air-water combination with varying water passage (spraying) were used as the quenching media in the quenching process of the castings. In order to evaluate the effect of five different quenching processes on the structure and mechanical properties of the castings, the method of light microscopy, Brinell hardness test and static traction test were used. Evaluation and porosity and SDAS quantifications were carried out by means of image analysis. Experiments did not prove right the hypothesis holding that low SDAS values inevitably mean higher mechanical properties of the castings. On the other hand, distinct is the negative influence of heterogeneous structure and porosity. Despite the fact that the heat treatment was successful in reducing the influence of structural inhomogeneities, it cannot be concluded that spray quenching has an utterly positive bearing on the mechanical and structural properties of the castings.
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Study of beta phase in Al-Mg-Si alloys by means of unconventional methods of electron microscopy
Ligas, Aleš ; Julišová, Martina (referee) ; Mikmeková, Šárka (advisor)
Aluminium Al-Mg-Si alloys are the most commonly used in automotive and construction industry. Hexagonal ’-phase is one of the metastable phases occured in this type of alloys. Unlike classic square -phase, this ’-phase is characterized by different crystalographic orientation to the matrix and shape. Standard method used for identification of aluminium alloys is scanning electron microscopy (SEM), because of its quickness and efficiency, but in case of very thin or damaged structures (as a result of metallographic process) it’s insufficient. Scanning low energy electron microscopy (SLEEM) can be appropriate for identification of mentioned precipitates due to its physical principles resulting in many advantages compared to SEM. So the most important benefits are interaction volume reduction (which leads to improvement of surface sensitivity), increase of material contrast (ability to change matrix / precipitates contrast) as well as crystalographic contrast.
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Low Cycle Fatigue of Magnesium Alloy AZ91
Julišová, Martina ; Podrábský, Tomáš (referee) ; Juliš, Martin (advisor)
The objective of the present study is to investigate the fatigue characteristics of cast magnesium alloy AZ91 after low–cycle fatigue tests at the indoor temperature. Squeeze casting specimens in both non–thermal treatment cast state and in solution annealing state were used as the experimental materials. Cyclic hardening/softening and fatigue life curves were obtained from the tests varying according to the way of thermal treatment. This bachelor thesis includes also fracture tests of specimens. Light microscopy and scanning electron microscopy were used for the investigation.
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Study of beta phase in Al-Mg-Si alloys by means of unconventional methods of electron microscopy
Ligas, Aleš ; Julišová, Martina (referee) ; Mikmeková, Šárka (advisor)
Aluminium Al-Mg-Si alloys are the most commonly used in automotive and construction industry. Hexagonal ’-phase is one of the metastable phases occured in this type of alloys. Unlike classic square -phase, this ’-phase is characterized by different crystalographic orientation to the matrix and shape. Standard method used for identification of aluminium alloys is scanning electron microscopy (SEM), because of its quickness and efficiency, but in case of very thin or damaged structures (as a result of metallographic process) it’s insufficient. Scanning low energy electron microscopy (SLEEM) can be appropriate for identification of mentioned precipitates due to its physical principles resulting in many advantages compared to SEM. So the most important benefits are interaction volume reduction (which leads to improvement of surface sensitivity), increase of material contrast (ability to change matrix / precipitates contrast) as well as crystalographic contrast.
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Influence of AlCr Layer to Fatiague Properties of Nickel Superalloy IN 713LC at the Temperature 800°C
Šulák, Ivo ; Julišová, Martina (referee) ; Podrábský, Tomáš (advisor)
The present diploma thesis is focused on the effect of AlCr layer on the low cycle fatigue behaviour of cast polycrystalline superalloy IN713LC at 800°C. Protective layer is made by chemical vapour deposition followed by heat treatment. Fatigue tests were conducted in strain control mode with constant total strain amplitude and strain rate. The fatigue behaviour is assessed by cyclic hardening/softening curves, cyclic stress-strain curves, Manson-Coffin curves and Basquin curves. Microstructure was observed in as-received state and also after cyclic loading by means of optical microscopy and SEM.
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