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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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An assessment of fracture behaviour of weld joints used in the power industry
Rádsetoulal, Milan ; Šiška, Filip (referee) ; Stratil, Luděk (advisor)
This thesis is focused on assessment of fracture behaviour of heterogeneous welded joint. The goal is to determine fracture behaviour at the interface of ferritic base metal and austenitic weld metal at temperature of 255°C. This kind of weld is widely used at energy industry. Fracture toughness was evaluated using CT specimens with size 0,5T in order to determine the initiation values of stable crack propagation. Fracture behaviour of the weld is correlated with results of metallography and fractography analysis. Both light and scanning electron microscopy is used for fractography analysis. An assessment of fracture behaviour of the interface of the weld joint is first of all connected with a need of suitable location of cycled crack to the interface of metals. In the case of well-prepared crack the lowest values of J-integral are observed. In other cases of slight crack deviation from the notch plane fracture values increase. Due to a large scatter of mechanical properties of heterogeneous weld joints an increased number of test specimens is needed to obtain relevant and conservative fracture toughness values. Correlation of fracture toughness with the results of fractography analysis leads to clarification of the crack trajectory and to description of fracture mechanism.
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An assessment of fracture behaviour of weld joints used in the power industry
Rádsetoulal, Milan ; Šiška, Filip (referee) ; Stratil, Luděk (advisor)
This thesis is focused on assessment of fracture behaviour of heterogeneous welded joint. The goal is to determine fracture behaviour at the interface of ferritic base metal and austenitic weld metal at temperature of 255°C. This kind of weld is widely used at energy industry. Fracture toughness was evaluated using CT specimens with size 0,5T in order to determine the initiation values of stable crack propagation. Fracture behaviour of the weld is correlated with results of metallography and fractography analysis. Both light and scanning electron microscopy is used for fractography analysis. An assessment of fracture behaviour of the interface of the weld joint is first of all connected with a need of suitable location of cycled crack to the interface of metals. In the case of well-prepared crack the lowest values of J-integral are observed. In other cases of slight crack deviation from the notch plane fracture values increase. Due to a large scatter of mechanical properties of heterogeneous weld joints an increased number of test specimens is needed to obtain relevant and conservative fracture toughness values. Correlation of fracture toughness with the results of fractography analysis leads to clarification of the crack trajectory and to description of fracture mechanism.
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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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