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Development of Models of Al Alloys Behaviour for Applications in Numerical Simulations of Welding and Heat Treatment
Vaněk, Mojmír ; Daněk, Ladislav (advisor)
The thesis deals with methodology for computational approaches for numerical simulations of welding and heat treatment of aluminium alloys. The thesis describes improvement of the current methodology for metallurgical part of the numerical analysis of welding, which is important mainly for prediction of dimensions of the heat affected zone (and deformations). The improvement was carried out based on CHD diagram that describes precipitation and dissolution of phases during continuous heating. The thesis also describes carried material measurements (measurement of chemical composition, dilatometric tests, tensile tests of several conditions of materials at temperatures up to 500 °C and measurement of aging curves), which allowed to significantly refine analysis results for the alloys EN AW-5083 and EN AW-6082. Based on an evaluation of the measurements, several conclusions were made. They can be useful for creation of material databases of other aluminium alloys. The thesis also describes quantification of dependence between tensile strength and yield strength on the Vickers hardness for different conditions of EN AW-6082. There is also methodology for numerical simulation of the heat treatment process of heat treatable Al alloys in the dissertation. The methodology is completely new approach which has never been published so far. Application of this method is based on user changes of the material database in software Sysweld after relatively easy measurement of aging curves. Therefore, the methodology can be considered as promising for application in industrial practice.
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Influence of Chemical Composition on Weldability of Structural Steels
Kachlíř, Jaromír ; Daněk, Ladislav (referee) ; Vaněk, Mojmír (advisor)
This work deals with the influence of chemical composition to weldability of construction steel S355, S275 and S235. The introduction is about marking steel according to norms EN 10027 and CSN 42 0002. It also marginally deals with the problematic of carbon equivalents, temperature of preheat and generation of martenzit during welding. The second half contains the evaluation of the examined steel samples. I focus mostly on mechanical properties, chemical composition and other steel charasteristics. All the samples are compared both to the other steels in its group and amongst each other.
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Prediction of welding joint distortion by computer simulation.
Vaněk, Mojmír ; Slováček, Marek (referee) ; Daněk, Ladislav (advisor)
In this master’s thesis there are set down dependencies of distortion of T-joints on the size of heat input and welding speed. Dependencies were found for single- and double-fillet welds, for single- and multiple-pass welding. The computer simulations were carried out in programs Visual-Weld and SYSWELD. The size of the melted zones, stress fields, material structure and hardness of the weld specimens were specified. Simulation results were compared with experimentally detected values.
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Electron beam welding technology
Skalka, Jan ; Vaněk, Mojmír (referee) ; Richter, Tomáš (advisor)
The bachelor thesis is devoted to analysis of electron beam welding technology. It is unconventional method of welding characterized by high quality weld and narrow heat-affected zone of welded parts. This technology, due to its development and qualities, has found its application in many industries, primarily in aviation and astronautics. The vacuum is limiting feature of this method and it is necessary for electron beam welding. However, even in this area, the development of new technologies have not stopped and generates concrete solutions to those problems. The thesis is also focused on elektron beam welding of rotary parts in the piece and serial production.
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Welding of turbine rotor materials
Palán, Marek ; Vaněk, Mojmír (referee) ; Daněk, Ladislav (advisor)
This thesis deal with the basic problems of welding rotor materials. It describe the essence of welding and ways of detecting defects caused by welding. Furthermore, it is covered in more detail the formation of heterogeneous welds and the impact of individual elements in the weld on the properties of the resulting weld. It lists detailed breakdown of creep-resistant steels and principles of their heat resistance. The thesis gives an overview of welding used in welding rotor materials and various methods are described. The work also includes commissioning of thermal processes in welding. In the experimental part is evaluated macrostructure, hardness and the method used in the implementation of the cladding material 26NiCrMoV14-5.
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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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Destructive methods of control of welding joints
Kopecký, Lukáš ; Richter, Tomáš (referee) ; Vaněk, Mojmír (advisor)
Bachelor´s thesis, the form of a literature review, discusses destructive inspection of welded joints. Using literary study of the issue, there are presented actual methods of destructive testing. The main aim of research is focused on describing the basic principles of the various destructive tests, their procedures, preparation of test samples and subsequent evaluation and comparison tests.
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Influence of welding parameters on angular distortion of weld
Crla, Tobiáš ; Vaněk, Mojmír (referee) ; Daněk, Ladislav (advisor)
The aim of this thesis is to qualify influence of welding parameters on angular distortion of weld. This thesis is divided into two parts - theoretical part and experimental part. The theoretical part is focused on solving causes of origin of tension and distortion during welding and on analysis of these causes. After the mentioned analysis there are also described solutions, how to prevent the potential origin of distortion and tension or how to proceed when these two phenomenas happen after all. In another section of this thesis there is term mentioned - method of welding MIG/MAG, because welding method is also affecting the origin of distortion and tension. Since this thesis is focused on angular distortion, there are theoretically described processes of this distortion and some methods of its assessment. These assessments are implemented also into the experimental part. In this part is practically examined influence of welding parameters on the angular distortion of weld on simple weldments. The measured values were compared to calculated values because of accuracy of measurement and verification of these values.
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Influence of welding parameters on a transverse distortion
Harmaniak, Daniel ; Vaněk, Mojmír (referee) ; Daněk, Ladislav (advisor)
In my bachelor thesis is described a theory of internal tensions and distortions during welding. My thesis also contains technological and structural principals used to minimalize them and methods used for elimination of internal tensions. There are also included calculated methods depending on the different parameters of welding concerning transverse distortions. A butt weld was done between two sheets of tin and its transverse shrinkage was measured. The measured value was compared with the calculated one.
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Cemented carbides
Vaněk, Mojmír ; Dvořáček, Jan (referee) ; Humár, Anton (advisor)
The aim of this bachelor thesis is a characteristic of uncoated and coated cemented carbides in terms of marking, structure, physical and mechanical properties. There is an overview of production methods of uncoated, coated cemented carbides and functionally graded hardmetals in the thesis. At the end there is an overview of the range of production of the most significant tool material producers including descriptions and areas of use of this materials.
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