TY - CONF A1 - Mente, Tobias A1 - Böllinghaus, Thomas ED - Sommitsch, C. ED - Enzinger, N. T1 - Numerical model for hydrogen assisted cracking in duplex stainless steel microstructures T2 - Mathematical modelling of weld phenomena 10 N2 - Duplex stainless steels (DSS) are used in various industrial applications, e.g. in offshore construction as well as in chemical industry. But, at specific conditions, as for instance arc welding fabrication, cathodic protection or exposure to sour service environments, such materials can take up hydrogen which may cause significant property degradation particularly in terms of ductility losses which, in turn, may entail hydrogen assisted cracking (HAC). If HAC occurs in a duplex stainless steel the cracking mechanism is different from steels having only one phase, because hydrogen diffusion, stress-strain distribution and crack propagation are totally different in the austenite or ferrite phase. Whereas, the mechanism of hydrogen assisted crack initiation and propagation as well as hydrogen trapping in DSS have not been fully understood up to the present, as in most two-phase microstructures. In order to better understand the mechanisms of hydrogen assisted cracking in duplex stainless steels, knowledge of the diffusion behavior and of the stress-strain distribution in the ferritic and austenitic phase is of great interest. A numerical mesoscale model was created with a view to studying the hydrogen transport and the stresses and strains in each phase of duplex stainless steel. The material investigated in this work was DSS 1.4462, consisting of approximately equal portions of ferrite and austenite. Hydrogen diffusion in the duplex base metal was studied using the finite element program ANSYS. Stress-strain distribution as well as hydrogen assisted cracking in the ferritic and austenitic phase fractions were additionally investigated. The results of numerical simulation of the hydrogen diffusion process as well as structural analyses enable the identification of crack critical areas in the DSS microstructure. Numerical simulations qualitatively reflect the crack initiation and propagation process in ferrite. Crack critical combinations of hydrogen concentrations and local mechanical loads initiating HAC can be identified. T2 - 10th International seminar numerical analysis of weldability CY - Leibnitz, Austria DA - 24.09.2012 KW - Schweißen KW - Mathematisches Modell KW - Numerische Mathematik PY - 2013 SN - 978-3-85125-293-4 VL - 10 SP - 337 EP - 356 PB - Verlag der Technischen Universität Graz AN - OPUS4-29987 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -