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Non-destructive testing of welds
Šaloun, Jan ; Sigmund, Marian (referee) ; Kubíček, Jaroslav (advisor)
This thesis describes non-destructive testing (NDT) of fusion welds of metals. There are five fundament methods of NDT discussed in the theoretical part – visual and magnetic particle inspection, ultrasonic, radiography and penetrant testing. Principles of methods, examining procedures and their evaluations are described. The methods are compared with each other. In the experimental part of the thesis two samples of welding joints were welded and tested by selected methods. To verify correctness of the indicated defects, metallographic samples were made. At the conclusion practical results are compared with theoretical statements.
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Welding of heterogeneous joints by laser
Charvátová, Eliška ; Mrňa, Libor (referee) ; Kubíček, Jaroslav (advisor)
This diploma thesis deals with welding of two dissimilar materials by laser. The samples were welded by direct beam guidance and wobbling, with and without using high alloy filler material and with the use of a diffusion barrier in the form of nickel. Welding was done with different shielding atmospheres. Nondestructive (VT, PT, UT-PA, RT) and destructive tests were performer (tensile test at room and elevated temperatures, microhrardness). Metalography was suplemented by EDX analysis of selected elements.
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Statistical support of the company management process
Kubíček, Jan ; Jankových, Róbert (referee) ; Maradová, Karla (advisor)
Master’s thesis describes statistical process control as a support for company management. Statistical process control methods and tools are introduced. Requirements for automotive industry are stated specifically for IATF 16949 standard and VDA 6.3 process audit method. Thesis presents current state in company Sanmina-SCI Czech Republic s.r.o regarding statistical regulation. Applies statistical process controls into the new process considering automotive requirements. It is all happening together with a new business introduction of automotive customer.
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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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Working of semi-finished product for laser welding
Černý, Jan ; Mrňa, Libor (referee) ; Kubíček, Jaroslav (advisor)
The thesis deals with the technology of laser welding and preparation of semi-finished products for laser welding for serial production. The theoretical part deals with the physical nature of the laser, different types of lasers, welding technology, preparation of welded surfaces, safety of work with lasers and basic division of corrosion resistant steels. The practical part deals with the assessment and evaluation of the proposed technologies of cutting blanks for laser welding. In the practical part, roughness, flatness and macrostructure tests were performed and evaluated.
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Plasma cutting of high strength steels
Šmak, Martin ; Herčík, Tomáš (referee) ; Kubíček, Jaroslav (advisor)
Cutting of steel is one of the fundamental operations within steel processing and steel product manufacturing. The cutting of high-strength steels represents a significant technological problem since the application of many methods produces an extensive amount of heat that is introduced into the material. The heat may significantly impact the mechanical properties of the steel. The thesis is focused on the application of the method of plasma cutting on high-strength steels. In the theoretical part of the present thesis, the common methods of cutting of steel and the plasma cutting technology are described. The parameters influencing the process of plasma cutting and their impact on the quality of the section are discussed. Furthermore, the concept of a heat-affected zone in the context of the plasma cutting method is concerned. The experimental part deals with the influence of plasma cutting on the hardness of certain types of high-strength steels. Three types of high-strength steels were used for the experiments: ARMOX 500 T, STRENX 650 MC E, and XAR®450. The sections were performed with two different cutting speeds. The size of the heat-affected zone and the hardness in the different areas of the section were evaluated. The results show that the plasma cutting is suitable for cutting of high-strength steels if appropriate parameters are selected. The influence of this method on the mechanical properties of certain high-strength steels is shown and discussed.
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Procedural parameters at Inconel 625 cladding
Hrádek, Jan ; Mrňa, Libor (referee) ; Kubíček, Jaroslav (advisor)
The research is focused on cladding of inconel 625 using the MAG - CMT method. It was found that welding without an oscillation does not create the necessary geometry to establish additional layers. When welding with an oscillation, it was researched that the current between 150 and 200 A appears most appropriate in the synergistic mode for welding inconel 625. The resulting weld bead was made at a current of 190 A with pulse dynamics correction set to -4 and correction of arc length to +10 and welding speed of 315 mm per minute.The weld bead was not ideal mainly due to insufficient height. The improvement of results could be achieved by set oscilation with fluent change in acceleration. Because of the time options and difficulty of programming it was used only constant speed for all experiments.
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Welding of galvanized sheets using hybrid Laser-TIG technology
Antes, Jiří ; Kubíček, Jaroslav (referee) ; Mrňa, Libor (advisor)
ANTES, Jiří: Welding of galvanized sheets using hybrid Laser-TIG technology This master thesis deals with the welding of zinced deep drawing steel using Laser-TIG technology. The first section of the thesis describes the topic from the theoretical point of view, which includes analysis of welding technologies, influence of used material and application of diagnostic methods. The second part of the thesis is focused on monitoring of welding current impact for weld quality of two types of joints.
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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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