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Microstructural Stability of Weld Joints of Austenitic and Ferritic Steels
Šohaj, Pavel ; Stránský, Karel (referee) ; Sopoušek, Jiří (referee) ; Foret, Rudolf (advisor)
This doctoral thesis summarizes the theoretical and experimental knowledge in the field of dissimilar weld joint of progressive austenitic and ferritic creep-resistant steels. The following materials were selected for the presented study: 316Ti stabilized austenitic stainless steel, martensitic 9-12 %Cr steel P92 and ferritic ODS steel MA 956. The main attention was focused on the long-term microstructural stability during high temperature exposure of heterogeneous joints of the austenite / ferrite type. The literature analysis critically evaluates the current state of knowledge in the field of microstructural stability of advanced creep-resistant steels weld joints. The practical experimental part was carried out in two directions. On the basis of the chemical composition phase equilibrium calculations were performed for each steel using the ThermoCalc software, giving the basic concepts about the dependence of the phase composition and the chemical composition of phases on temperature. In parallel with these calculations the laboratory joints 316Ti/P92 made by resistance welding and the MA 956/316Ti electron beam weld joints were prepared, analyzed in as-weld state and further annealed at different temperature conditions. Exposed joints were subjected to microstructure and phase analysis. The stability of the weld interface was mainly observed. Attention was also focused on the agreement between the calculation and experimental data in comparison with data published in the literature. Based on the calculations, experimental results and published data the suitability of the combination of materials is discussed in the thesis and reasoning about the behavior of studied weld joints during long-term high temperature exposure was formulated. Based on the results the expected degree of microstructural stability of 316Ti/P92 joint was confirmed, while the joints MA 956/316Ti were found to be unstable.
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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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HSS welding process automation in nuclear power plant
Charvátová, Eliška ; Mrňa, Libor (referee) ; Kubíček, Jaroslav (advisor)
The bachelor thesis compares the manual and mechanized method of welding in the production of dissimilar weld joint. The samples were welded from austenitic and ferritic-perlitic parent materials with using the same type of high alloy filler material. Joint geometry is identical for both methods. Nondestructive and destructive controls were performed, the structural changes in the materials given by the different amounts of heat transfer into the weld joint were compared. Increasing the corrosion resistance of the inner pipe surface is ensured by nickel layer.
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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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HSS welding process automation in nuclear power plant
Charvátová, Eliška ; Mrňa, Libor (referee) ; Kubíček, Jaroslav (advisor)
The bachelor thesis compares the manual and mechanized method of welding in the production of dissimilar weld joint. The samples were welded from austenitic and ferritic-perlitic parent materials with using the same type of high alloy filler material. Joint geometry is identical for both methods. Nondestructive and destructive controls were performed, the structural changes in the materials given by the different amounts of heat transfer into the weld joint were compared. Increasing the corrosion resistance of the inner pipe surface is ensured by nickel layer.
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Microstructural Stability of Weld Joints of Austenitic and Ferritic Steels
Šohaj, Pavel ; Stránský, Karel (referee) ; Sopoušek, Jiří (referee) ; Foret, Rudolf (advisor)
This doctoral thesis summarizes the theoretical and experimental knowledge in the field of dissimilar weld joint of progressive austenitic and ferritic creep-resistant steels. The following materials were selected for the presented study: 316Ti stabilized austenitic stainless steel, martensitic 9-12 %Cr steel P92 and ferritic ODS steel MA 956. The main attention was focused on the long-term microstructural stability during high temperature exposure of heterogeneous joints of the austenite / ferrite type. The literature analysis critically evaluates the current state of knowledge in the field of microstructural stability of advanced creep-resistant steels weld joints. The practical experimental part was carried out in two directions. On the basis of the chemical composition phase equilibrium calculations were performed for each steel using the ThermoCalc software, giving the basic concepts about the dependence of the phase composition and the chemical composition of phases on temperature. In parallel with these calculations the laboratory joints 316Ti/P92 made by resistance welding and the MA 956/316Ti electron beam weld joints were prepared, analyzed in as-weld state and further annealed at different temperature conditions. Exposed joints were subjected to microstructure and phase analysis. The stability of the weld interface was mainly observed. Attention was also focused on the agreement between the calculation and experimental data in comparison with data published in the literature. Based on the calculations, experimental results and published data the suitability of the combination of materials is discussed in the thesis and reasoning about the behavior of studied weld joints during long-term high temperature exposure was formulated. Based on the results the expected degree of microstructural stability of 316Ti/P92 joint was confirmed, while the joints MA 956/316Ti were found to be unstable.
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