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oai:www.ideals.illinois.edu:2142/83926 2023-07-11 col_2142_5131 col_2142_14787 com_2142_5130 com_2142_9630 com_2142_234

Sofronis, Petros Dadfarnia, Mohsen 2015-09-25T21:12:44Z 2015-09-25T21:12:44Z 10000-01-01 2009 2009 To further explore the influence of hydrogen on ductile fracture, we model sustained-load cracking in the iron-base superalloy 1N903 at hydrogen pressures at which fracture is governed by plasticity. Through a micromechanics analysis, we quantify the void growth dependence on stress triaxiality and hydrogen-induced material softening as a function of position ahead of a crack tip. Correlation of the calculated void diameters with experimentally measured ones leads to the identification of a microstructural length that characterizes the onset of hydrogen-induced cracking. Lastly, to analyze the mechanics of sustained-load cracking at pressures greater than 100 MPa for which experiments suggest that hydrogen promotes failure by intergranular cracking, we simulate crack propagation by cohesive finite element methodology based on hydrogen-induced decohesion thermodynamics. The results reveal a number of issues related to the complexity of the failure mechanism and the robustness of the cohesive element approach. Made available in DSpace on 2015-09-25T21:12:44Z (GMT). No. of bitstreams: 2 license.txt: 4848 bytes, checksum: 96035ab3f5e1c23cc7138a224ce498bd (MD5) 3362764.pdf: 4641988 bytes, checksum: 8f4452f0eb828914c97227132d318752 (MD5) Previous issue date: 2009 Embargo set by: Seth Robbins for item 85207 Lift date: Forever Reason: Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs U of I Only 188 p. Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2009. http://hdl.handle.net/2142/83926 (MiAaPQ)AAI3362764 eng Engineering, Metallurgy Micromechanics of Hydrogen-Induced Crack Initiation in Pipeline Steels and Subcritical Crack Growth text Mechanical Engineering Mechanical Engineering University of Illinois at Urbana-Champaign Dissertation Ph.D.