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Evaluation of bearing steel´s microstructural parameters with regards to their mechanical properties and lifetime
Hroš, Michal ; Juliš, Martin (referee) ; Klakurková, Lenka (advisor)
The aim of this bachelor thesis is evaluating the impact of microstructural parameters of bearing materials with an emphasis on evaluation carbidic phase with using protocol SEP 1520. Literary section analyzes the specific groups of materials for the manufacture of rolling bearings, specifically focusing on steel, where is discussed their performance, production, heat treatment, micropurity, microstructure and macroscopic requirements. Work on structure of bearing steel as well as the experimental part of the thesis is focused on a more detailed description carbidic phase materials and the systematic evaluation with regards to type of initial a semifinished product for the manufacture of bearings, the heat treatment, the resulting mechanical properties and especially durability.
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Analysis of degradation processes of the shock absorber rod
Sýkorová, Jitka ; Juliš, Martin (referee) ; Klakurková, Lenka (advisor)
The bachelor thesis deals with the analysis of degradation processes of the rods of the synchronizer generator. The theoretical part deals with the description of the generator, the analysis of the material, the properties of the brass for the production of the absorber rod and the possible parameters influencing its degradation. The experimental part of the thesis analyzes damaged bars of the shock absorber using destructive and non-destructive techniques, suggests non-destructive testing in-field and determines the dependence of electrical properties on the structure.
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Fracture behaviour of heat affected zone near heterogeneous weld joint
Jelínek, Vladimír ; Válka, Libor (referee) ; Juliš, Martin (advisor)
The study deals with mechanical characteristic of heterogeneous weld joint. The low carbon steel 22K and austenitic steel have been used as a experimetnal materials. The low carbon steel has special properties in basic condition. The sample has been evaluated in basic condition and after annealation. There have been evaluated impact of annealation proces to structure and mechanical charakteristics in experimental part of study. The particularised analysis of microstructure has been done by pictorial analysis. Mechanical characteristics has been examinated in both conditions by 2 different methods – measurment of microhardness according to Vickers and test of fracture toughness on compact tension specimens.
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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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Corrosive Degradation of Austenitic Steels
Vykoukalová, Tereza ; Juliš, Martin (referee) ; Klakurková, Lenka (advisor)
The main requirement imposed on stainless steel is a high corrosion resistance in aggressive environment. The main aim of the thesis is a numerous group of corrosion resistance stainless steels, i.e. the stainless steel with austenitic matrix. Increased attention is paid to the corrosive attack and corrosion rate of three chosen materials with austenitic matrix in four different corrosive environments (30% solutions of sulphuric acid, nitric acid, acetin acid and sodium chloride). The method of light microscopy was used to study corrosive degradation of different materials.
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Composite materials used in the manufacture of cars
Rendek, Marek ; Juliš, Martin (referee) ; Němec, Karel (advisor)
Bachelor’s thesis deals with various types of composites used in the spheres of automotive industry. In the first section, it’s focused on the introduction to issues of composite materials, methods of production, their advantages and disadvantages. The second part of thesis focuses on specific applications in the automotive industry. In the final part there is a future evaluation and an overall view of the composite materials in the automotive field.
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The Image Analyses Utilization at Nickel-base Superalloy Degradation Classification
Řičánková, Veronika ; Juliš, Martin (referee) ; Němec, Karel (advisor)
During operational conditions of internal combustion turbines of turbojet engines, the impeller blades are stressed by load cycles which vary in time, temperature and stress. In the course of operation, the blades are exposed to a considerable number of degradation effects, particularly high-temperature corrosion, fatigue processes and creep. The presented work is aimed at the study of the structure cast nickel-base superalloy INCONEL 713 LC, creep tests exposured. The structural changes (degradation) was clasifikation by the help of image analyses. Operational conditions of heat parts, used in gas turbines and turbo-compressors, were simulated by creep tests of Inconel 713 LC nickel superalloy during a constant load of temperatures ranging from 750 up to 950C. Changes in the structure dependent upon time, temperature and stress applied were analysed by means of light and electron microscopy methods and image analyses after the fracture of test bars.
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