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Determination of the Mechanical Properties of Weld Materials based on Hardness Test
Stodola, Martin ; Španiel, Miroslav (referee) ; Dlouhý, Ivo (referee) ; Junek, Lubomír (advisor)
This dissertation thesis deals with determination of the mechanical properties of weld materials based on instrumented hardness test. This work was caused by the research project between IAM Brno Ltd and CEZ corp., when the task was to develop a methodology for evaluation of mechanical material properties using NDT methods. For these reasons the development of methodology is reflected especially for use in practice focusing to determining the mechanical properties of the heterogeneous weld joint on the assembled equipment. The mechanical material properties are determined by carrying out non-destructive tests of the instrumented Vickers hardness. The developed methodology for determining of basic mechanical properties is based on the principle of inverse FEM modeling of the instrumented hardness tests, when output of the testing is indentation curve and measured surface imprint after unloading. The basic material mechanical properties are achieved by comparing the outputs of the experimental instrumented hardness tests and the outputs of the modeled hardness test using FEM.
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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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Determination of the Mechanical Properties of Weld Materials based on Hardness Test
Stodola, Martin ; Španiel, Miroslav (referee) ; Dlouhý, Ivo (referee) ; Junek, Lubomír (advisor)
This dissertation thesis deals with determination of the mechanical properties of weld materials based on instrumented hardness test. This work was caused by the research project between IAM Brno Ltd and CEZ corp., when the task was to develop a methodology for evaluation of mechanical material properties using NDT methods. For these reasons the development of methodology is reflected especially for use in practice focusing to determining the mechanical properties of the heterogeneous weld joint on the assembled equipment. The mechanical material properties are determined by carrying out non-destructive tests of the instrumented Vickers hardness. The developed methodology for determining of basic mechanical properties is based on the principle of inverse FEM modeling of the instrumented hardness tests, when output of the testing is indentation curve and measured surface imprint after unloading. The basic material mechanical properties are achieved by comparing the outputs of the experimental instrumented hardness tests and the outputs of the modeled hardness test using FEM.
|
|
|
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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