Please use this identifier to cite or link to this item:
http://hdl.handle.net/11375/27314
Full metadata record
DC Field | Value | Language |
---|---|---|
dc.contributor.advisor | Kish, Joey | - |
dc.contributor.advisor | McDermid, Joseph | - |
dc.contributor.author | Wojnas, Caroline Theresa | - |
dc.date.accessioned | 2022-01-26T14:27:13Z | - |
dc.date.available | 2022-01-26T14:27:13Z | - |
dc.date.issued | 2021 | - |
dc.identifier.uri | http://hdl.handle.net/11375/27314 | - |
dc.description.abstract | The microstructure of steel is well known to affect hydrogen-induced cracking (HIC) susceptibility by having certain heterogeneities serving as effective hydrogen trap sites. A consensus on whether or not fine-scale niobium carbide (NbC), nitride (NbN) and carbonitride (Nb(C,N)) precipitates can behave as effective hydrogen traps has yet to be established. The H-trapping capacity of Nb precipitates in a Fe-C-Mn-Nb model steel was investigated with the goal of minimizing embrittlement effects and improving the design of X70 pipeline grade steel for sour service oil and gas applications. First, a heat treatment was applied to the model steel to change the Nb-based precipitate size distribution, which was subsequently characterized via transmission electron microscopy, electron energy loss spectroscopy, and atom probe tomography. The experimental heat treatment increased the number of fine-scale precipitates (<15 nm) that are ideal for APT characterization. NbN and NbC precipitates of various stoichiometries were confirmed within the steel. Further, a custom electrolytic H-charging device was designed, fabricated, and validated using thermal desorption spectroscopy. Additionally, the extent of galvanic corrosion between NbC and NbN and the steel matrix was determined using custom scaled-up particle matrix specimens. Potentiodynamic polarizations conducted using active and passivating electrolytes revealed the relative nobility of the materials. Both NbC and NbN particles were more noble than the steel matrix; thus, possessing driving force for galvanic corrosion, with the particles serving as cathodes. Future studies involving electrolytic charging of the steel in a D-based electrolyte coupled with atom probe tomography will facilitate the direct observation of H-trapping sites relative to various Nb-based precipitates and contribute to an improved understanding of the mechanisms governing HIC. | en_US |
dc.language.iso | en | en_US |
dc.subject | Corrosion resistance | en_US |
dc.subject | Hydrogen-induced cracking (HIC) | en_US |
dc.subject | High strength low alloy (HSLA) | en_US |
dc.subject | Nb content | en_US |
dc.title | Influence of Fine-scale Niobium Carbonitride Precipitates on Hydrogen-Induced Cracking of X70 Pipeline Steel | en_US |
dc.type | Thesis | en_US |
dc.contributor.department | Materials Science and Engineering | en_US |
dc.description.degreetype | Thesis | en_US |
dc.description.degree | Master of Science in Materials Science and Engineering (MSMSE) | en_US |
Appears in Collections: | Open Access Dissertations and Theses |
Files in This Item:
File | Description | Size | Format | |
---|---|---|---|---|
Wojnas_Caroline_T_2021 December_MASc in Materials Science and Engineering.pdf | 11.31 MB | Adobe PDF | View/Open |
Items in MacSphere are protected by copyright, with all rights reserved, unless otherwise indicated.