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Modelling of hydrogen diffusion in power station steels and influence of experimental conditions on the determination of diffusion coefficients

  • In the field of modelling hydrogen assisted cracking (HAC) phenomenon, hydrogen diffusivity is an important input parameter for numerical simulation. In terms of hydrogen diffusion coefficients, they have great impact on realistic assessment of the evolution of possible crack critical hydrogen concentrations. In addition, the chemical compositions of steels can have a strong effect on hydrogen diffusion. Unfortunately, literature provides a wide range of available hydrogen diffusion coefficients even for similar microstructures and equal temperatures. The scattering of the data can lead to significant deviations in the results of simulating the evolving hydrogen concentrations due to hydrogen uptake (by fabrication or service). Thus, the application of such data to crack-models or for component life tie predictions can be realized up to the present only by considering envelope curves of such value, corresponding to a work or bench case scenario, respectively. For improved reliabilityIn the field of modelling hydrogen assisted cracking (HAC) phenomenon, hydrogen diffusivity is an important input parameter for numerical simulation. In terms of hydrogen diffusion coefficients, they have great impact on realistic assessment of the evolution of possible crack critical hydrogen concentrations. In addition, the chemical compositions of steels can have a strong effect on hydrogen diffusion. Unfortunately, literature provides a wide range of available hydrogen diffusion coefficients even for similar microstructures and equal temperatures. The scattering of the data can lead to significant deviations in the results of simulating the evolving hydrogen concentrations due to hydrogen uptake (by fabrication or service). Thus, the application of such data to crack-models or for component life tie predictions can be realized up to the present only by considering envelope curves of such value, corresponding to a work or bench case scenario, respectively. For improved reliability of numerical simulaitons, it is necessary to minimize the mentioned deviation of these data. Hence, this work focuses on the validation of hydrogen diffusion coefficients obtained from permeation experiments at room temperature. Two baintic steels with different alloying concepts were investigated, the creep-resistant 7CrMoVTiB10-10 and the reactor pressure vessel grade 20MnMoNi4-5. A numerical model is presented for simulation of the corresponding hydrogen diffusion during permeation experiments using the finite element software ANSYS. Three different diffusion coefficients (obtained from different common calculation methods) are considered and compared to numerical results. The vases of thes calculation methods are permeation transients which are a direct measure for hydrogen. The results of the simulated hydrogen diffusion coefficients show that only one procedure for calculation of diffusion coefficitnes is suitable in comparision to the experimental values. Thus, it is suggested to use this method for analysis of experimental results in case of hydrogen diffusion during permeation experiments. Furthermore, this work supplies validated values for the hydrogen diffusion coefficients of both steel grades.zeige mehrzeige weniger

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  • Mathematical Modelling of Weld Phenomena 11 Contents_Titelblatt.pdf
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Metadaten
Autoren/innen:C. Münster, Tobias Mente, Michael Rhode, Thomas Böllinghaus
Persönliche Herausgeber/innen:C. Sommitsch, N. Enzinger, P. Mayr
Dokumenttyp:Beitrag zu einem Sammelband
Veröffentlichungsform:Verlagsliteratur
Sprache:Englisch
Titel des übergeordneten Werkes (Englisch):Mathematical Modelling of Weld Phenomena 11
Jahr der Erstveröffentlichung:2016
Organisationseinheit der BAM:9 Komponentensicherheit
9 Komponentensicherheit / 9.4 Integrität von Schweißverbindungen
Verlag:Technische Universität Graz
Verlagsort:Graz
Erste Seite:435
Letzte Seite:457
DDC-Klassifikation:Technik, Medizin, angewandte Wissenschaften / Ingenieurwissenschaften / Ingenieurwissenschaften und zugeordnete Tätigkeiten
Freie Schlagwörter:Creep-resistant Steel; Diffusion Coefficient; Hydrogen; Numerical Simulation; Permeation; Pressure Vessel Steel
Themenfelder/Aktivitätsfelder der BAM:Material
Material / Degradation von Werkstoffen und Materialien
Material / Materialien und Stoffe
ISSN:2410-0544
ISBN:978-3-85125-490-7
Verfügbarkeit des Volltexts:Volltext-PDF im Netzwerk der BAM verfügbar ("Closed Access")
Datum der Freischaltung:10.01.2017
Referierte Publikation:Nein