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The quality of welded joints of iron alloys - the causes of defects and the consequences of their presence
Korábová, Vendula ; Juliš, Martin (referee) ; Klakurková, Lenka (advisor)
The aim of the bachelor thesis is to become familiar with the standards mapping the quality testing of welded joints and the follow-up application of these standards in solving a case study. The theoretical part describes welding methods, changes in the microstructure of the welded joint depending on temperature, heat dissipation rate and heat treatment. A major part is devoted to the mapping of standards describing destructive and non-destructive testing of welded joints. The experimental part deals with a comprehensive analysis of three case studies. The contents are components with localized failure in the welded joint. Emphasis is placed on determining the cause of the damage based on analyses of chemical composition, microstructure and hardness measurements.
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Snow chains manufacturing
Bořek, Pavel ; Kubíček, Jaroslav (referee) ; Císařová, Michaela (advisor)
This thesis is aimed at investigating the snow chain manufacturing process with a closer focus on the problematic spot related to the heat affected zone, weld and base metal. In the theoretical part, the issue of resistance welding and the metallurgical processes involved in the formation of a resistance weld are described for a better understanding of the nuances in the practical part where a structural analysis of the weld area in terms of microstructure, macrostructure and hardness is carried out. For this part, chain samples after welding, carburizing, quenching, tempering and zinc electroplating are used.
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Structural analysis of austenitic weld joints
Procházka, Robert ; Foret, Rudolf (referee) ; Havlík, Petr (advisor)
The bachelor thesis deals with structural analysis of austenitic weld joints by using methods of material science. The theoretical part of the thesis summarizes the problematics of welding of high-alloy steels. After the general definition of welding and weldability of high-alloy steels, the thesis focuses on structural adjustments including welding defects during the welding process. Selected methods of fusion welding that were used to create these welds are mentioned in the second half of the theoretical part. The experimental part covers the structural analysis of the welds, which consists of microstructure evaluation, chemical composition analysis, and microhardness test.
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Design of a portable machine for machining large diameter pipes
Boháč, Josef ; Pavlík, Jan (referee) ; Tůma, Jiří (advisor)
This diploma thesis deals with the design of a portable machine for machining large diameter pipes. This thesis is divided into research, calculation, design, and construction parts. The introductory part is devoted to research in the field of joining large diameter pipes, with a focus on flanged and welded joints. Based on the findings from the research part, several construction solutions were considered. In the next part, the most suitable design solution was selected using a multicriteria analysis technique and subsequently elaborated on in detail. The following chapter deals with the calculation of maximal cutting forces and the selection of motor. An air motor was chosen as the most suitable option for the proposed machine. This part is followed by the computational part, which includes strength calculations for the critical parts of the machine. The final part of the thesis is devoted to the construction itself and the description of the individual construction nodes of the machine. The thesis also includes a 3D model, drawings of selected parts, and an assembly drawing.
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Footbridge
Smělíková, Petra ; Puchner, Josef (referee) ; Sýkora, Karel (advisor)
The topic of my Bachelor's thesis is a static assessment of a bearing structure of a current footbridge which is also used for cycling. It is placed in Kunovice near Uherské Hradiště. The length of span is 28 meters. Its construction is solved as space framework with through-span. Main beam is truss structure with upper saddle flange. The height of beam in the middle of the span is 2.5 meters and above supports is 1.5 meters. The calculation is done either by hand or using calculation program Scia Engineer 2012.0.
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Structure and properties of weldment of rotor steels
Jech, David ; Jan,, Vít (referee) ; Foret, Rudolf (advisor)
The object of this thesis is to assess the structural stability of heterogeneous weld joint, which consists of two different base materials (16,537 steel and 16,236 steel) and weld metal NiCrMo2.5-IG with buttering layer P24-IG. All these materials belong to the group of low-alloyed creep-resistant steels that are to be used mainly in the power industry. The weld joint was made by application of the TIG hot wire welding method. Structural stability of this joint was evaluated by carbon redistribution and microstructural changes after annealing in temperature 300 °C and 400 °C during 500 hours. For modelling the phase composition of particular steels was used the ThermoCalc software. All gained results should be employed to appraise whether the heterogeneous weld joint of the steam turbine´s rotor is eligible for long-term operation in hard working conditions.
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Structural Stability of Creep-Resistant Steels and their Weldmets
Šohaj, Pavel ; Jan, Vít (referee) ; Foret, Rudolf (advisor)
The structural stability of creep-resistant steels P22, P91 and Eurofer´97 and structural stability of weld joint P22/P91 have been studied. The microstructural changes during annealing at temperatures of 500 – 900°C were examined. The state of equilibrium have been simulated using the ThermoCalc software. The computed results were compared with published data. A good agreement between the simulation and the published data was observed.
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Trade House in Brno
Serbousková, Kateřina ; Sýkora, Karel (referee) ; Barnat, Jan (advisor)
The final thesis deals with the design of the steel loadbearing structure of the shopping center situated in Brno. The built-up floor area is 1973 m2 (L-shaped ground plan with dimensions 48 m x 50 m). The construction consists of three parts. Building A has four above-ground floors and reaches a height of 25.5 m. The steel structure of mono-pitched roof is designed in two options. Both options consist of full-length purlins and truss girders. Building B is a single-storey building with a mono-pitched roof top reaching 8.1 m high. Building C is three-storey with a flat roof. The first floor has a construction height of 4.5 m and the remaining two floors reach height of 3.6 m, which coincide with building A. The steel structure is made of steel-concrete composite ceilings and pin-supported columns. In the case of bracings, pressure was eliminated by means of non-linearities.The work includes proposal, assessment of the supporting structure and calculation of the directional details. Internal forces were determined based on a static analysis in the SCIA Engineer calculation program.
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Utilization of laser welding methods for fixation of electrotechnical sheet bundles
Adam, Tomáš ; Kubíček, Jaroslav (referee) ; Mrňa, Libor (advisor)
Thesis deals with individual technologies of packaging stator sheets and their use in practice. The greatest emphasis is placed on welding technologies, especially on the differences between the individual methods. The experimental part of the thesis is focused on finding suitable parameters for welding the stator package using a laser with a special wobling head. The samples were evaluated in terms of penetration depth, the number of defects, especially pores and grain coarsening.
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Analysis of welded joints after fatigue tests
Kučera, Ondřej ; Doubrava, Marek (referee) ; Havlík, Petr (advisor)
This bachelor thesis deals with analysis of welded joints after fatigue tests . The first part of this thesis, literary research, discusses weldability of carbon steels and low-alloy steels and effect of chemical composition on weldability of materials. Further there are zones of welded joints, their microstructure and mechanisms applied described in this thesis. There are defects occurring in welded joints and their common causes and remedies described in the part of literary research dealing with defects. And the final part of the literary research deals with material fatigue, fatigue of welded joints and effect of defects, fusion zone and heat-affected zone on the fatigue of welded joints. In the experimetal part of bachelor thesis there is described experimental material, results obtain process and discussion of results.
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