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Issues of the LaserHybrid welding method
Znášik, Samuel ; Sigmund, Marian (referee) ; Kubíček, Jaroslav (advisor)
The thesis deals with the issue of using LaserHybrid welding for the energy industry where the combination of laser and arc could facilitate higher quality welds resistant to aggressive environments, corrosion and oxidation. The methods that the hybrid process produce as well as possible replacements for the MIG and MAG methods are explored, as well as the different configurations and their possible impact on the process. The possible use of the technology for hyperbaric welding is also presented. The experimental part is devoted to the welding of refractory martensitic steel used in the power industry for the production of steam turbines. Weld structures at different parameters were investigated and hardnesses were compared.
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Use of torch swing for butt weld welding of stainless steel MAG method
Gago, Matúš ; Sigmund, Marian (referee) ; Kubíček, Jaroslav (advisor)
Diploma thesis of arc welding of stainless steels focused on the MAG method, with a literature study on the issue. The geometries of the butt weld with the preparation of the bevel "Y" and the thickness of materials that are often used on structures used in the energy and food industries (6, 8 and 12 mm) were selected. An experimental study of the effect of MAG welding was performed, with and without oscillation of the welding torch for the "Y" weld. Experimentally verified sample welds of individual types were supplemented by the evaluation of results with fillet welds and submerged arc welds for comparing the consequences of welding with high heat input. The materials used were theoretically evaluated, the possible resulting theoretical material structure was analytically calculated and the results were included in the Scheaffler and WRC 1992 diagram. The mutual weldability of the materials with the equivalent of Crom and Nickel was assessed. And evaluated macrostructure of weld patterns, developed tensile tests and hardness tests to assess the impact of mechanical properties. In the end, recommendations for practice and recommendations for the prevention of errors, which were observed on experimental samples, were set.
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The problems of welding stainless steel 1.4541
Šmarda, Vladimír ; Sigmund, Marian (referee) ; Kubíček, Jaroslav (advisor)
This thesis focuses on austenitic steel welding in the upper part of a steam generator at the nuclear power station Dukovany, and the suitable technology when replacing this part. Part of this thesis is dedicated to the progressive methods TIG, such as the use of hot wire or orbital welding of pipe parts. The experiment in this thesis project tests the optimal parameters setup when welding while using a modified TIG method; a motor-fed hot wire with a welding source from EWM manufacturer was used in this project. Number of NDT tests, along with destructive tests including metallographic tests, demonstrated and verified that the methods, the additional materials and the way the experiment was carried out were chosen correctly and proved effective. These tests also included the hardness of the welding point and TOO locations. The experiment assessment part summarizes the experiment execution, describes the results of the tests, and recommends further continuation in the process toward WPQR
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Production of the material chamber to a blast furnace
Netopil, Lubomír ; Kubíček, Jaroslav (referee) ; Sigmund, Marian (advisor)
The theses deals with the production of furnace-top hopper. Mainly it is focused on the welding of abrasion-resistant materials and steel for pressure vessels using the FCAW method. These materials are described in detail in the research section, including the additional materials used, the welding methods used and NDT tests used to check the quality of the welds. The practical part then describes the technological process of production. Subsequently, the procedure of welding of the abrasion-resistant steels and steel for pressure vessels, including the developed WPS, is elaborated. The procedure of testing by non-destructive tests of selected combinations of materials with documented test reports and a plan of inspections and tests is also described. Finally, a technical and economic evaluation of production was performed.
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Weldability problems of duplex mixer blades
Bryksí, Petr ; Záděra, Antonín (referee) ; Sigmund, Marian (advisor)
The diploma thesis deals with the analysis of the causes of fracture of axial stirrer blades made of duplex material 1.4462 for gypsum suspension in Ledvice Power Plant. The theoretical part deals with the problem of welding of duplex steels. The practical part of the work includes the procedure from the preparation of the sample for metallographic, fractographic observation, chemical composition and hardness test. For our experiment, areas at the fracture point were cut out from the supplied blades and then measurements were made on them. Subsequently, we then evaluated the measured data at the fracture site of the blades and the weld joint area. Based on the analysis, technological and design recommendations for further blade production were made.
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Optimalization of the welding process for low - pressure tubular sets
Urbánek, Štěpán ; Kubíček, Jaroslav (referee) ; Sigmund, Marian (advisor)
The diploma thesis examines the implementation of the production process of low-pressure pipe sets for hydraulic aggregates in the company Bosch Rexroth. The first part presents a literature analysis of used technologies and basic welded materials. The second part focuses on selected subprocesses ensuring the production and proposals for their streamlining. It includes a summary of responsibilities across departments and a template for processing the necessary technical documentation for the smooth running of production. Another proposal includes a technological procedure for practical verification of the production, which simultaneously serves as a basis for measuring the welding time. The reason for the implementation of this production was the extended delivery time of pipe sets from suppliers and possible financial savings. The practical part is concluded with a technical and economical evaluation, which expresses the possible financial savings in the production of low-pressure pipelines instead of the current state involving the cooperation with suppliers.
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Nickel alloy overlay welding parameters optimalization
Lauš, Lukáš ; Kubíček, Jaroslav (referee) ; Sigmund, Marian (advisor)
The aim of these master's thesis is to choose and optimize parameters of the Venturi tube throat weld cladding. The Venturi tube is made from carbon steel ASME SA-106 Grade C. The weld cladding is performed by plasma transferred arc welding. The throat is weld overlaid with nickel base powder Inconel 625. The overlays are made without oscilation. The main requirement was to find a maximum possible powder feed rate and others welding parameters to develop maximum welding speed and productivity on automat. Visual and penetrant testing on the overlays were performed. Metalographic samples were prepared. On the samples was meassured dilution, overlay thickness and width of the heat affected zone. Results are compared with parameters succesfully used in the cooperating company.
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Elimination of oxide rising during aluminum alloys welding
Vagunda, Pavel ; Kocich, Radim (referee) ; Sigmund, Marian (advisor)
This diploma thesis deals with the search of reason causing production of oxides in the welded joint, which have an impact on defects formation. The objective was to identify the areas in the technological process that can have the biggest impact on the oxides generation. The following areas of the technology process were selected: the length of storage time, the influence of the welder and the participation of the arc cleaning effect. The simulation imitating these effects was processed on Y and HY type welds with incomplete penetration. Subsequently, macroscopic inspection was provided to supply the most data used for evaluation. Defects in the root of the weld, caused by the oxides formation, appeared in the majority of the samples. From the evaluation was concluded, that the highest elimination is achieved by a significantly increased cleaning effect of the arc. Other influences didn‘t prove significant difference. The results were followed by an evaluation and solution proposal. The best solution seems to be adjusting the location of the weld on the blank, so that the weld root is fully penetrated. As a result, the welded joint isn‘t subject to the negative effects associated with oxides.
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Materials change of parts for harvester chain production
Houdek, Radim ; Kubíček, Jaroslav (referee) ; Sigmund, Marian (advisor)
The work is focused on the track element, namely the replacement of the crossbar material from steel 27MnCrB5-2 to steel 30MnB5 from which the other parts of the cell, the cubes, and the bar are made and welded by the GMAW method. Changing the material and omitting the preheating phase would reduce the production time of the cell by approximately half the time. The theoretical preheating temperature calculated according to the relevant standard for both steels exceeded 200 ° C. Test specimens imitating the weld between the crossbar and the cube were welded on which a qualitative evaluation was performed. These were weldments of 30MnB5 steel with preheating (sample 10), 30MnB5 steel without preheating (sample 11) and 27MnCrB5-2 steel with preheating (sample 9). In terms of macrostructure, non-penetrations were found on all samples. Martensitic structure was found in all areas by microstructural observation. When measuring the hardness according to the Vickers method, approximately the same hardness profile was obtained in all weld areas of samples 10 and 11. The highest value reached 450 HV1 and exceeds the maximum hardness recommended by the standard. Due to very similar test results for 30MnB5 steel weldments with and without preheating, it is possible not to perform preheating. However, the results may be skewed by the relatively small size of the test specimens. For a reliable evaluation and final decision, it is necessary to perform tests on a real crossbar after complete production.
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3D metal printing by wire welding methods
Přibyla, Dalibor ; Izák, Josef (referee) ; Sigmund, Marian (advisor)
This thesis presents the most commonly used technologies of 3D metal printing by wire welding methods, like WLAM, EBAM and WAAM. Deals with their principles, sub methods, applications, suppliers and also with current researches and trends, which are focused on deposition of thin layers. CMT technology is closely described, with attention on its certain kinds, like Cycle step, Advanced, Pulse Advanced, Pin and Braze+. Then, the CMT workplace at IMID DREAD, FME BUT is described by individual components, automatization and robotization. Final evaluation shows, that the chosen workplace is appropriate for required 3D print of magnesium alloys and overhanging structures, due to cold metal transfer technology and low purchase price.
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