Hydrogen in Low Carbon Steel: Diffusion, Effect on Tensile Properties, and an Examination of Hydrogen’s Role in the Initiation of Stress Corrosion Cracking in a Failed Pipeline
| atmire.migration.oldid | 1237 | |
| dc.contributor.advisor | Shaw, W. J. D. | |
| dc.contributor.author | Eggum, Troy Justin | |
| dc.date.accessioned | 2013-08-20T21:14:03Z | |
| dc.date.available | 2013-11-12T08:00:12Z | |
| dc.date.issued | 2013-08-20 | |
| dc.date.submitted | 2013 | en |
| dc.description.abstract | This thesis covers three topic areas: hydrogen diffusion in steel, hydrogen effects on steel’s mechanical properties, and examination of a pipeline that fractured due to stress corrosion cracking (SCC). A hydrogen diffusion experiment using low carbon steel, passive hydrogen charging (5% NaCl, 1.1 pH, N2 deaeration), and mercury eudiometry for hydrogen measurement was used to develop a concentration profile in a specimen. This profile was compared to an analytical solution to Fick’s Law of Diffusion. The experimental concentration profile follows Fick’s prediction and allows determination of hydrogen’s effective diffusion coefficient and surface and bulk concentrations. The effective diffusion coefficient and surface concentration were found to increase with aggressiveness of the charging solution. Tensile tests were performed on low carbon steel from a mobile solute in solid solution perspective. Different combinations of values of strain rate and hydrogen concentration were used to determine the effect of hydrogen concentration and to find interactions between hydrogen diffusion rate and strain rate. Increasing the strain rate increased the flow stresses (yield, ultimate, and fracture), uniform plastic strain, and strain hardening exponent. Increasing the hydrogen concentration decreased necking strain, elongation at fracture, and increased fracture stress. This led to a natural division of the tensile response of the steel into two areas: prior to the ultimate changes to the strain rate dominate the material’s behaviour and post-ultimate where changes in hydrogen concentration dominate the material’s behaviour. It was shown that hydrogen had a hardening effect near the yield point and softening effect near the ultimate, indicating that these techniques can detect changes in the competing embrittling and plasticizing processes of solute hydrogen in steel. Crack morphology was examined on a SCC fractured pipeline both from axial and radial directions to observe relationships between corrosion pits and the crack field. The pitting and cracking processes were observed to be separate events. It is likely that pitting occurred first, generating hydrogen, which then moved into the steel. When sufficient hydrogen was present, the steel became sensitized to the applied hoop stress and oriented crack fields developed which eventually led to a large fracture. | en_US |
| dc.identifier.citation | Eggum, T. J. (2013). Hydrogen in Low Carbon Steel: Diffusion, Effect on Tensile Properties, and an Examination of Hydrogen’s Role in the Initiation of Stress Corrosion Cracking in a Failed Pipeline (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/26402 | en_US |
| dc.identifier.doi | http://dx.doi.org/10.11575/PRISM/26402 | |
| dc.identifier.uri | http://hdl.handle.net/11023/881 | |
| dc.language.iso | eng | |
| dc.publisher.faculty | Graduate Studies | |
| dc.publisher.institution | University of Calgary | en |
| dc.publisher.place | Calgary | en |
| dc.rights | University of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission. | |
| dc.subject | Materials Science | |
| dc.subject.classification | Hydrogen | en_US |
| dc.subject.classification | Diffusion | en_US |
| dc.subject.classification | Pipeline | en_US |
| dc.subject.classification | Stress Corrosion Cracking | en_US |
| dc.subject.classification | Fick's Law | en_US |
| dc.subject.classification | Tensile Test | en_US |
| dc.subject.classification | Corrosion | en_US |
| dc.title | Hydrogen in Low Carbon Steel: Diffusion, Effect on Tensile Properties, and an Examination of Hydrogen’s Role in the Initiation of Stress Corrosion Cracking in a Failed Pipeline | |
| dc.type | doctoral thesis | |
| thesis.degree.discipline | Mechanical and Manufacturing Engineering | |
| thesis.degree.grantor | University of Calgary | |
| thesis.degree.name | Doctor of Philosophy (PhD) | |
| ucalgary.item.requestcopy | true |