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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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Influence of humic acids on the corrosion behavior of low carbon steel
Horák, Tomáš ; Buchtík, Martin (referee) ; Doskočil, Leoš (advisor)
This diploma thesis deals with influence of humic acid from lignite on corrosion behavior of low carbon steel S235JR in the environment of 0,1 M NaCl at three diffrent pH values (5, 7 and 9). Humic acid was fractionated into three soluable fractions at pH 5, 7 and 9. Corrosion behavior was studied by potentiodynamic polarization, electrochemical impedance spectroscopy and immersion tests. Surface analysis of low carbon steel was carried out before and after corrosion tests as well as analysis of corrosion medium. The results show that humic acid has negative effect on corrosion of low carbon steel in comparison with 0,1 M NaCl solution, because in presence of humic acid, the corrosion rate is higher. The negative effect was attributed to the formation of complexes of humic acid with released iron ions. The main corrosion product on the surface of low carbon steel after exposure to the 0,1 M NaCl was magnetite. Presence of humic acid in 0,1 M NaCl caused formation of lepidocrocite as main corrosion product. Potencial mechanism that is trying to clarify the formation of corrosion products and influence of humic acid on corrosion behavior is discussed in this thesis.
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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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Steels for the automotive industry
Boček, Jan ; Mauder, Tomáš (referee) ; Štětina, Josef (advisor)
The subject of this thesis is research of usage of modern steel in the automotive industry. Because car bodies are subjected to strict requirements, multiple steel grades are used in their construction. Steel provides suitable properties such as good weldability, formability, and high strength. It has its disadvantages as well, and because of that, other materials has started to be used. This thesis contains a general overview about steel, the theory of usage of steel in the automotive industry and information about specific steels used and their properties. Particularly they are HSLA steels, low carbon steels, dual phase steels and TRIP steels. Nowadays in the automotive industry, steels are the main material used and it isn’t unreasonable to think that it will stay that way in the future.
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Steels for the automotive industry
Boček, Jan ; Mauder, Tomáš (referee) ; Štětina, Josef (advisor)
The subject of this thesis is research of usage of modern steel in the automotive industry. Because car bodies are subjected to strict requirements, multiple steel grades are used in their construction. Steel provides suitable properties such as good weldability, formability, and high strength. It has its disadvantages as well, and because of that, other materials has started to be used. This thesis contains a general overview about steel, the theory of usage of steel in the automotive industry and information about specific steels used and their properties. Particularly they are HSLA steels, low carbon steels, dual phase steels and TRIP steels. Nowadays in the automotive industry, steels are the main material used and it isn’t unreasonable to think that it will stay that way in the future.
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Influence of humic acids on the corrosion behavior of low carbon steel
Horák, Tomáš ; Buchtík, Martin (referee) ; Doskočil, Leoš (advisor)
This diploma thesis deals with influence of humic acid from lignite on corrosion behavior of low carbon steel S235JR in the environment of 0,1 M NaCl at three diffrent pH values (5, 7 and 9). Humic acid was fractionated into three soluable fractions at pH 5, 7 and 9. Corrosion behavior was studied by potentiodynamic polarization, electrochemical impedance spectroscopy and immersion tests. Surface analysis of low carbon steel was carried out before and after corrosion tests as well as analysis of corrosion medium. The results show that humic acid has negative effect on corrosion of low carbon steel in comparison with 0,1 M NaCl solution, because in presence of humic acid, the corrosion rate is higher. The negative effect was attributed to the formation of complexes of humic acid with released iron ions. The main corrosion product on the surface of low carbon steel after exposure to the 0,1 M NaCl was magnetite. Presence of humic acid in 0,1 M NaCl caused formation of lepidocrocite as main corrosion product. Potencial mechanism that is trying to clarify the formation of corrosion products and influence of humic acid on corrosion behavior is discussed in this thesis.
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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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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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