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Cobalt alloys and their weld ability
Herčík, Tomáš ; Mrňa, Libor (referee) ; Sigmund, Marian (advisor)
The bachelor thesis is focused on the evaluation of the current state of use of cobalt and cobalt alloys. Due to its shortage and the growing need for precious metal for the production of Li-on batteries, its price, which is now almost at silver prices, is also rising. Some countries even described it as critical and they have bought it in large quantities. From 2020, it is expected that all cobalt will be reserved for the automotive industry, where the use of cobalt in batteries increases their capacity. It is therefore time to look for ways in which precious metal is economised in existing applications. This also includes welding. Of the existing welding technologies, laser welding looks to be the best. In this case no additional material is needed which reduces the need for cobalt. This technology was verified in the experimental part and evaluated by destructive tests (microhardness, microstructure, macrostructure).
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Optimization of welding parameters during laser welding with additional cold wire
Venc, Jan ; Kubíček, Jaroslav (referee) ; Mrňa, Libor (advisor)
This diploma thesis deals with the optimization of process parameters of welding a drainage channel using a laser beam with an additional cold wire. This channel is made of austenitic Cr Ni stainless steel X5CrNi 18-10 (1.4301, ČSN 17 240) with a sheet thickness 1,5 mm. Mechanical properties of samples were checked by using transverse tensile test. Subsequently, the samples were macroscopically inspected focusing on dimensions of the weld and the presence of weld defects. Finally, the structure of the weld metal and fundamental material was evaluated by using microscopic control. Based on evaluation tests, the optimal welding parameters were recommended.
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Welding of 22MnB5 steel using Laser-TIG hybrid technology
Krejčí, Adam ; Sigmund, Marian (referee) ; Mrňa, Libor (advisor)
This thesis deals with usage of hybrid technology Laser-TIG for welding of boron enhanced steel 22MnB5. This thesis evaluates the influence of preheating using technology of TIG arc welding to a weld quality in comparison with laser welds. In practical part of thesis there were 1,8 mm metal sheets of 22MnB5 welded. This metal sheet specimens were welded by using constant parameters of laser with varying parameters of TIG technology. There were 12 specimens of sheet metal created including 3 specimens using only laser and 9 specimens using Laser-TIG hybrid technology while varying magnitude of current (I=20 A, 40 A a 60 A). Welds created this way were evaluated by tensile test and strength limits compared. Then metalografic survey was carried out examining macro and microstructure. Results of metalografic survey were confronted with Vickers hardness test.
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Study of weld plasticity of deep-drawn sheets welded by Laser-TIG technology
Kutil, Petr ; Kubíček, Jaroslav (referee) ; Mrňa, Libor (advisor)
This thesis is focused on laser welding and hybrid laser-TIG welding. The first part contains a brief theoretical description of these technologies. Standard quality and plasticity tests of welded joint are also mentioned. The second, experimental part, centres on the study of plasticity of tailored blanks (made of different types of HSLA steel), that are welded with laser and laser-TIG technology. The aim of the thesis is to assess process parameters effect on weld suitability for following deep drawning operation. Based on the calculated and measured figures obtained from the experiment, the most suitable welding parameters were chosen.
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Welding of aluminum alloys using high-power semiconductor laser
Mikeš, David ; Kubíček, Jaroslav (referee) ; Mrňa, Libor (advisor)
Thesis deals with the optimization of process parameters during laser welding of aluminum alloys 5000 series. The theoretical part describes the types of lasers and their applications in industry, further discusses the properties of aluminum alloys, laser welding theory and principles of monitoring and diagnostics of laser process. In the experimental part the samples were welded using a semiconductor laser. For those samples were evaluated mechanical properties, welded defects and structure depending on the process parameters. Using the photodetector was observed stability of laser process by sensing the plasma plume. The link between stability and the formation of structural defects in the weld joint was observed from the measurement results.
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Automation of a workplace for laser welding
Elger, Jiří ; Kubela, Tomáš (referee) ; Pochylý, Aleš (advisor)
The goal of this diploma thesis on the topic of „Automation of workplaces for laser welding“ is the design of a robotic manipulation device for a four position laser welder which has been designed for a real project for automotive parts company. The introduction part of this work analyses the assignment and describes the current state of the workplace, describes each work cycle operation and customer requirements at the workplace. The work then deals with solving individual key nodes at the workplace, including introducing this robot and end effector design. The conclusion of this work explains safety solutions at the workplace, and financial and technical evaluation.
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Laser welding of the abrasive steel
Berka, Roman ; Kubíček, Jaroslav (referee) ; Mrňa, Libor (advisor)
This project, elaborated within the master degree presents plates welding. Based on the literature study the problems of laser welding were designed optimal welding parameters. The material, on which were in the experimental part test and geometry analysis performed was steel Hardox 400 with thickness 5 mm. These welds were compared with welds made by MAG. Equipment used for werding was fiber laser.
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Use of laser-TIG hybrid technology for welding of different materials used in power engineering
Žák, Tomáš ; Beran, David (referee) ; Mrňa, Libor (advisor)
Thesis is focused on analyzing the influence of preheating process parameters using electric arc from TIG torch during laser welding on weld properties of stainless steel and carbon steel with higher strength. In this thesis experiment was done in which metal sheets 3 mm thick from X12Cr13 and S355 steels were welded. Welding was done first with using only laser, then laser with TIG preheating and lastly laser with preheated material by induction heater. When TIG preheating was used than set welding current was changed on the power source. The welds were subsequently evaluated based on macrostructure, microstructure and Vickers hardness test.
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