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Comparison of manual laser and TIG welding
Černý, Jan ; Sigmund, Marian (referee) ; Kubíček, Jaroslav (advisor)
The diploma thesis deals with the comparison of TIG welding methods (141) and unconventional methods of manual laser welding (51) of thin sheets of stainless steel X5CrNi 18-10. The goal of the thesis is to determine the difference in quality between the selected methods on the welds made and to develop a technical and economic evaluation. At the beginning of the diploma thesis, a literary study is analyzed with a focus on the principle of individual welding methods, possible defects arising during welding and the weldability of individual types of stainless steels. In the experimental part, the design of the experiment is discussed, which consisted in welding samples of selected weld joints using individual technologies. The welds were then evaluated using non-destructive and destructive tests. Finally, the economic evaluation of both technologies and the return of the equipment were also calculated.
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Working of semi-finished product for laser welding
Černý, Jan ; Mrňa, Libor (referee) ; Kubíček, Jaroslav (advisor)
The thesis deals with the technology of laser welding and preparation of semi-finished products for laser welding for serial production. The theoretical part deals with the physical nature of the laser, different types of lasers, welding technology, preparation of welded surfaces, safety of work with lasers and basic division of corrosion resistant steels. The practical part deals with the assessment and evaluation of the proposed technologies of cutting blanks for laser welding. In the practical part, roughness, flatness and macrostructure tests were performed and evaluated.
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Dependence of the laser weld geometry on the bevel size
Man, Antonín ; Kubíček, Jaroslav (referee) ; Mrňa, Libor (advisor)
This work deals with laser welding technology. It explains in more detail advantages and disadvantages, applications and direction in which this relatively young technology develops. The main topic of this work is welding of martensitic stainless steel with carbon structural steel. Components of this type can be found, for example, in the power industry, specifically the stator part of a steam turbine. Part of this work is also an experiment that will explain the dependence of the geometric dimensions of the material to be welded on the quality of the weld. The welded test specimens were subsequently tested by both the non-destructive and destructive methods. It can be stated from the results, that the size of the bevel does not affect the quality of the weld, nor geometry.
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Segregation during solidification in austenitic-ferritic stainless steels
Kejha, Richard ; Čech, Jan (referee) ; Pernica, Vítězslav (advisor)
The master thesis deals with processes of segregation in austenitic-ferritic stainless steels. The introductory part consists of characteristics features of austenitic-ferritic steels and theoretical analysis of segregation processes. The second part shows practical measurements of segregation in experimental casting. Macrosegregation was measured on a spectrometric analyzer and simultaneously solved in the simulation program MAGMA. The aim of this thesis is to verify the effect of solidification time and dwell time between liquidus and solidus temperature on the chemical heterogeneity of duplex stainless steel casting of about 500 [mm]. Chemical heterogeneity was solved for selected alloying and accompanying elements such as C, Mo, Ni, Mn, Cr. The microsegregation was not addressed. Comparison of the mechanical properties of cast and heat treated duplex steel was done by tensile testing of samples cut from the center of the casting.
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Production and properties of austenitic steels
Líkař, Martin ; Bořil, Petr (referee) ; Ostratický, Marek (advisor)
The bachelor thesis describes production of austenitic steels and their properties. First part of thesis contains general overview of austenitic steels and their division according to chemical composition. The second part includes production, which deals with secondary metallurgy. The third part deals with properties of austenitic steels, where is mentioned their use in practise. The aim is to develop research describing production, properties and composition of austenitic steels in view of their utilization.
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Corrosion resistant and heat resistant steels
Kříž, Petr ; Tulka, Jaromír (referee) ; Molliková, Eva (advisor)
This bachelor thesis deals with stainless steels and heat resistant steels. It speaks about their chemical composition, heat treatment, structure and options of its practical usage in various fields. One of its parts is also focused on corrosion in general, corrosion types, economic impacts, kinds of corrosion attacks and factors which affect her.
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Macrosegregation and microsegregation in austenitic CrNi steels
Ostratický, Marek ; Čech, Jan (referee) ; Záděra, Antonín (advisor)
This diploma thesis deals with segregation cycles in austenitic CrNi steels. In first section deals with theory of macrosegregation and microsegregation cycles. The second part is focused on this cycles in experimental casting. Macrosegregation was measured by spectrometric analyser and by MAGMA simulation program. Microsegregation was measured by electron microscope. The aim of this diploma thesis is verify the influence of setting conditions on heterogenity chemical composition in austenitic CrNi steel. For experimental casting with a wall thickness of about 500 mm will be verified effect of the setting time, residence time between solid and liquid phases and others parameters for macrosegregation and microsegregation in selected elements.
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Decarburisation and degassing of high-alloyed Cr steels under vacuum
Ertelt, Tomáš ; Pernica, Vítězslav (referee) ; Záděra, Antonín (advisor)
The work deals with the investigation of the effects of vacuum degassing and decarburization in high alloyed stainless steel. The reason for this is to increase corrosion resistance and mechanical properties. The theoretical part is devoted to the analysis of options to reduce carbon, nitrogen, hydrogen and manganese at atmospheric pressure and in vacuum. In experimental part there is the description of melting, calculation of conditions facilitating reduction of oxide inclusions as a function of the gas pressure in the furnace and the evaluation of the influence of vacuum on the content reduction of carbon, nitrogen and manganese.
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Effective milling of stainless steels using octagonal inserts
Kouřil, Petr ; Sedlák, Josef (referee) ; Zemčík, Oskar (advisor)
Thesis aims on efficient milling of stainless steels. Groups of these steels are characterized and their machinability is analyzed in theoretical part of this thesis. In the practical part of thesis were face milled stainless steels ČSN 17 240.4 a ČSN 17349.4. There are evaluated edge durability, roughness of surface, loading of total cutting force and effectiveness of test tools.
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