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Weldability of steels for steam turbine parts
Jech, David ; Hutařová, Simona (referee) ; Juliš, Martin (advisor)
The aim of contemporary standard welding technologies is to create compact welds with high value of solidity and toughness in laboratorial and operational conditions. This welding technology is asserted in new creep - resisting steels on basis of steel CrMoV and CrMoNiV, which have high value of solidity and creep - resistance. The thesis deals with problems connected with the weldability of steels for steam turbine rotors and it´s aim is to interpret the structural and mechanical features of the weld joint for material combinations under consideration. For the assessment of weld joint features has been used measuring of micro hardness and hardness according to Vickers, microstructure was observed by methods of light microscopy.
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Modern trends in radiographic procedures and methods in defectoscopy
Skřivánková, Vendula ; Vlašic, František (referee) ; Juliš, Martin (advisor)
Presented thesis deals with modern trends and techniques in radiographic methods of crack detection which are recently used in engineering practice. In the first part, conventional (analogue) radiography principles based on creating a visible image of tested object to radiographic film are discussed. The next part is aimed to the digital radiography and radioscopy. To digitize existing X-ray film images, application of storage phosphor plates (CR), flat panels (DR) and computed tomography (CT).
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Optimization of manufacturing of iron castings to reduce the quantity of defects
Blaha, Marek ; Brázda, Zdeněk (referee) ; Juliš, Martin (advisor)
The presented diploma thesis is focused on defects of castings as well as optimization of production with the aim of reducing the number of defective products. The theoretical part is focused on basic information about cast iron and its production, structure and mechanical properties. Another part of this thesis describes the defects of castings and options for non-destructive testing of cast iron castings. In the experimental part are analyzed three sorts of defective casting. Castings for testing were provided by JMA s.r.o. foundry. The summary contains tests results and proposals for optimization of production.
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Modern methods in nondestructive testing of materials using ultrasound
Šimeček, Radek ; Stránský, Lubomír (referee) ; Juliš, Martin (advisor)
Theme of this bachelor thesis is nondestructive testing of materials by modern ultrasound methods. In the first part are mentioned defects of mechanical components, which can be detected by ultrasound. This is followed by a description of conventional ultrasound technique, including a list of the major disadvantages and limits. In the second part are analyzed the modern ultrasonic methods TOFD and Phased Array. It describes not only the principle of these techniques, but there are also provided practical examples of their application.
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Methods to increase the visibility of the original austenite grain boundaries in steels
Gamanov, Štěpán ; Klakurková, Lenka (referee) ; Juliš, Martin (advisor)
This thesis deals with methods of revealing prior austenite grains in steels. The objective was to describe and demonstrate these basic methods on samples. The theoretical part deals with the importance of austenite grain and its size, with description of base methods of revealing austenite grains, and with methods of determination of grain size. The practical part consists of pictures and commentary of samples wich were made with some of the base methods described in the theoretical part. Conclusion consists of comparison of our and external results and also expanding commentary on individual methods.
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Optimization of the structure and properties of materials for motorcycle parts
Stárek, Jan ; Němec, Karel (referee) ; Juliš, Martin (advisor)
The aim of this study is to review the materials used on selected motorcycle components. The present bachelor thesis concerned with comparison of serial parts and alternative variants for racing. Describes the production of specific components and studying some of their material characteristics. Justifies the potential use of non-traditional manufacturing technologies. Each chapter is dedicated to elements pursued by the use of special attention during operation of motorcycle. The main part of the experimental testing of levers and sprockets from different suppliers. The work is also illustrated by the choice and use of two different materials on one component. The selected components are subjected to material tests.
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Structure and Properties of Aluminium Cast Alloys
Samek, Petr ; Podrábský, Tomáš (referee) ; Juliš, Martin (advisor)
The bachelor work is focused on favour of relationship between structure and porperties of aluminium cast alloy AlSi7Mg0,6 in dependence of the effect of cooling rate. The AlSi7Mg0.6 alloy is commonly used in foundry industry to produce high stressed automotive components like motor blocks and cylinder heads. The properties of the material correspond directly to their microstructure which is given by the parameters of the solidification process. Within the frame of experiment were got structural characteristics (DAS, porosity) depending up on method of cooling. There were watched location of structure defects in volume of specimens.
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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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Modern diagnostic methods use in defectoscopy
Vítámvás, Zdeněk ; Stránský, Lubomír (referee) ; Juliš, Martin (advisor)
Nowadays non-destructive testing offers various ways to detection defects in material. By selecting of suitable method or suitable combination of tests we can locate the defect and determine size of defect with sufficient accuracy. For higher probability of detect defects and for easier operation and evaluation are still evolve new ways of inspection. There are summarizes both ordinarily and modern methods using in defectoscopy in this work. There are describe its principles, courses of testing, suitability of use and there are drop next general information.
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