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Porosity during welding aluminous alloys
Hájková, Alena ; Daněk, Ladislav (referee) ; Sigmund, Marian (advisor)
This thesis deals with the problem of occurrence of porosity in aluminous alloys and the methods of their repair in the company IFE. Theoretical part is aimed on the current state of porosity and the ways in which the be pores can be repaired. Used technologies of repairs are TIG welding and cementing. The practical part consists of experiment in which is used a method of cementing on specific part.
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Structual welding of aluminium alloy
Blahák, Petr ; Hála, Michal (referee) ; Kubíček, Jaroslav (advisor)
The project elaborated in frame of engineering studies branch 2303R002 presents a project that contains welding a structure made of aluminium alloy. There were two usable methods selected, based on literal study of welding aluminium alloys, TIG welding and friction welding, and these were compared with alternative methods of joining, hard soldering and bonding. A work procedure was made for TIG method, soldering and bonding and four experimental joins were made thereafter. Project compares these methods mainly in economical way, also in way of technological difficulties and in way of observance the strength of base materials. Project also deals with problems with lowering strength of base material in heat affected area, burn out of thin material, tendency of aluminium to fill with hydrogen, quick oxidation and consequent hard surface layer emerging on the aluminium.
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Manual versus orbital GTAW piping welding
Hofbauer, Jan ; Kubíček, Jaroslav (referee) ; Sigmund, Marian (advisor)
In thesis are compared options of stainless steel piping welding, orbital and manual version of method GTAW and GMAW. At the beginning, these methods are described theoretically and after that there are described materials used for fabrication two test welds on austenitic steel piping of diameter 168 mm. The first weld was made by orbital method GTAW, the second one by manual method GMAW. Next, these two welds are compared based on defects, welding parameters and width of heat affected area. The conclusion is that both welds are defect-free and because of economical aspects is better to use orbital GMAW method for this diameter of piping.
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Welding problems of the „press chamber“ component
Čermák, Petr ; Dohnal, Ivo (referee) ; Kubíček, Jaroslav (advisor)
Petr Čermák: Welding problems of the "press chamber" component The goal of this work is to produce the "press chamber" component of a food industry machine and selection of a suitable arc welding method, a base and a filler material. Practical part of this work includes technological design of a weldment production process considering all the know-how concerning welding technology, heating process of a stainless steel and a weld quality testing. Especial emphasis is put on analyzing of deformations and residual stresses during welding and taking countermeasures to reduce these undesired defects in the "press chamber" weldment made of high alloy austenitic steel. The final output is the "press chamber" component and a welding jig design reducing occurrence of the undesired deformations or residual stresses.
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Compared HAZ the methods of welding TIG, MAG and CMT
Šoulák, Petr ; Sigmund, Marian (referee) ; Kubíček, Jaroslav (advisor)
The bachelor thesis was to compare the HAZ size for the TIG, MAG and CMT methods. The welded materials were low carbon steel and austenitic stainless steel. Samples of 250x50 mm size and 2 mm thick were welded with butt weld without a gap. In the first part of experiment, samples were welded at the same welding speed. The second part concerned only CMT, where the optimal welding speed was used. For selected samples, the HAZ size was measured and compared in macroscopic images.
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Weldability of steels for the manufacture of bicycle frames
Grim, Robert ; Richter, Tomáš (referee) ; Vaněk, Mojmír (advisor)
This thesis is focused on steel materials used in bicycle frame manufacturing. The alloys are analysed based on their mechanical properties as well as their weldability. Steel materials are divided into three groups corresponding to the foremost frame manufacturers. Alloys with trade names are paired with equivalent normalized materials selected according to their chemical composition. The weldability of individual steels is addressed in several chapters sorted by materials’ mechanical properties and structure. The work further explains why TIG welding of frames is preferred and what the method’s main advantages are.
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Study of properties of laser welds of Hardox 450 material using arc preheating
Debs, Martin ; Kubíček, Jaroslav (referee) ; Mrňa, Libor (advisor)
In this thesis is studied the influence of arc TIG preheating during laser welding of 2 mm Hardox 450 material sheets. This material achieves its good mechanical properties by processes of heat treatment. That causes problems during welding because of heat degradation. Experimental sheets were welded within various configurations of welding parameters and positions of TIG nozzle. Testing specimens were cut out by laser and were used for tension testing, Vickers hardness testing and metallographical testing (macro and microstructure). The results of using the second heat source are: wider heat affected zone, smoother transitions among its zones, reduction of toughness and hardness, finer grain structure and occurring ferritic microstructure. This hybrid technology, combination of laser welding and TIG preheating, is very productive creating joints with greatly good quality. The thesis also contains a comparison with common MAG welding method.
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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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Unconventional methods of welding of wrought magnesium alloys
Klimčáková, Kateřina ; Mrňa, Libor (referee) ; Doležal, Pavel (advisor)
Master's thesis deals with consideration possibility of conventional and unconvetional welding methods of wrought magnesium alloys. Methods of Friction Stir Welding, Pulsed Nd:YAG laser and Continuous Fiber laser was used to join magnesium alloy sheets AZ31, AZ61, ZE10 and ZE41. For studying influence of processing parameters on microstructure and mechanical properties were used methods of light microscopy, scanning electron microscopy, tensile tests and microhardness measurements. The results of tensile tests show that from the point of view of keeping ultimate tensile strength is the best methods for welding magnesium alloys Friction Stir Welding. Compared with Nd:YAG laser, fiber laser give better properties of welds. From comparing microstructure and mechanical properties . It wasn't found publications about Friction Stir Welding of magnesium ZE alloys or about FSW sheets with thickness only 0,8 mm and 1,6 mm.
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Progress of welding in shipbuilding
Urban, Václav ; Kubíček, Jaroslav (referee) ; Kovář, Petr (advisor)
This work deals with the methods of welding in shipbuilding, summarises the basic techniques used for welding of the SAW, MAG, MIG, TIG, laser, Laser-Hybrid. It describes the properties of welded material. Especially the materials HY80 and HY100. It follows from the filler materials. In particular materials Spoolarc 95 and 120. Particular emphasis is placed on the method of Laser-Hybrid, its properties and use in shipbuilding. Finally, describes the method of welding aluminium using FSW, preparation of welded surfaces and producting of sandwich panels.
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