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Welding of deep-drawing steels with protective layer by laser-TIG hybrid technology
Brehovský, Patrik ; Sigmund, Marian (referee) ; Mrňa, Libor (advisor)
The diploma thesis focuses on laser welding of extra deep-drawn steel sheet according to the standard WSS-M1A365-A14 with a protective zinc surface layer. A 0,9 mm thick steel sheet with a zinc layer with coating weight 50 g · m^-2 is welded by a hybrid welding method Laser-TIG. The laser, as the primary energy source, is used for welding the material. The arc, provided by a non-melting tungsten electrode, is used for preheating the material for melting and evaporation of the zinc layer. Based on the initial experiments, the magnitude of the laser power with the welding speed was chosen as a constant parameter. The magnitude of the electric current, as the variable parameter, was set up to 0, 20, 30 and 40 ampers for welding the lap and the butt welds. Only one piece of the each weld type combination was made. The welds were afterwards tested to verify their quality and material properties. The first differences between laser welding with or without TIG preheating were visible during the experiment. The positive effects of the laser welding with preheating by TIG were confirmed. The material properties of the joints achieved better values and a influence of the welding defects on the quality of the joints was reduced. The Laser-TIG is a good choice for welding galvanized steel sheets in the mass production of automotive industry and it could be improved by more researches.
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Influence of fluxes on weld metal properties
Holub, Kamil ; Sigmund, Marian (referee) ; Kubíček, Jaroslav (advisor)
This thesis deals with the topic of submerged arc welding – an electric arc method of fusion welding, that uses a layer of granulated flux to shield the weld pool from atmospheric gases. Theoretical part is devoted to the description of the welding method and fluxes currently used. The practical part contains an experiment, which consists of making two weld deposits on structural steel S235JR by using different fluxes. First weld deposit is made with OK 10.62 Flux. The same flux alloyed with the Tribaloy T-800 laser cladding powder is used for the second weld deposit. Test specimens are examined on the basis of influence of fluxes combined with a single electrode wire.
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Welding thin-walled pipes made of stainless steels
Naď, Tomáš ; Sigmund, Marian (referee) ; Kubíček, Jaroslav (advisor)
The bachelor's thesis deals with technology of welding of thin-walled stainless steel pipes and the analysis of weldability of stainless steels. The theoretical part provides a basic description of the material's weldability and the basic defects in welding, the characteristics of stainless steels, their division, marking, alloying and a general overview of their weldability. The experimental part describes selected welding technologies used for the production of thin-walled stainless steel pipes (LBW, PAW, HFIW). Finally, the technology used to weld the presented samples of thin-walled pipes is ascertained and the macrostructure of the weld are compared.
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Examination of degradation frequently repaired shearing and forming tools
Izák, Josef ; Kubíček, Jaroslav (referee) ; Sigmund, Marian (advisor)
The diploma thesis is focused on the renovation of forming tools made of tool steel, their weldability and assessment of the quality of tool repairs. The damaged tool was a part of the cutter from the progressive cutting tool made of Caldie steel. We used micro TIG technology to repair the damage. A total of three types of additional materials were used and investigated to restore the geometry of the damaged edge. One of the main purposes was to evaluate the possibility of extending the life of tools and reducing the implementation of already inefficient repairs. A number of destructive tests were performed for the assessment - macrostructure, microstructure, hardness measurement and EDS analysis.
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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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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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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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Use of the preheating by electric arc during laser welding of steels with higher carbon content
Mach, Martin ; Sigmund, Marian (referee) ; Mrňa, Libor (advisor)
The thesis is focused on the study of the use of electric arc preheating, in this case source WIG, during laser welding of steel with a higher carbon content, specifically for this work steel 1.1191 thickness 2 mm. Based on the calculation of the carbon equivalent, the preheating was determined to 208 °C. The welding parameters were selected on the basis of the first experiments. In the experimental section, the samples were welded with laser with preheating using a source WIG, which were then made to a tensile test, Vickers microhardness, macrostructure and microstructure. By using a second heat source, the heat-affected area of the samples was expanded. Samples that cracked in the middle of the weld during the tensile test were heat influenced by cutting samples. The remaining samples was broken in the base material, thus the weld produced was of good quality. Combination of laser welding with WIG electric arc preheating is a very productive method over conventional methods and one of the few pre-heating solutions for laser welding. These are the initial experiments for the use of the WIG arc for preheating in laser welding, to be followed by further research, mainly for the automotive industry.
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CMT advanced application in industrial practice
Šoulák, Petr ; Sigmund, Marian (referee) ; Kubíček, Jaroslav (advisor)
In presented diploma thesis is studied problematics of welding of high strength steels. This work also describes arc welding in protective atmosphere CMT Advanced. In experimental part of this work is CMT Advanced method compared with conventional arc welding in protective atmosphere in shortcut mode used for welding of Hardox 450 and Weldox 700 E. Comparing of mechanical properties of weld material are realized via transverse tensile testing and measuring of microhardness. Macrostructure and microstructure of weld was evaluated too. In the last part of this thesis is a brief economical assessment of both studied methods.
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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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