Creep damage assessment of ex-service 12% Cr power plant steel using digital image correlation and quantitative microstructural evaluation

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dc.contributor.authorVan Rooyen, Melodyen_ZA
dc.contributor.authorBecker, Thorstenen_ZA
dc.contributor.authorWestraadt, Johanen_ZA
dc.contributor.authorMarx, Geneveveen_ZA
dc.date.accessioned2019-09-26T10:17:57Z
dc.date.available2019-09-26T10:17:57Z
dc.date.issued2019
dc.descriptionCITATION: Van Rooyen, M., et al. 2019. Creep damage assessment of ex-service 12% Cr power plant steel using digital image correlation and quantitative microstructural evaluation. Materials, 12(19):3106, doi:10.3390/ma12193106.
dc.descriptionThe original publication is available at https://www.mdpi.com
dc.descriptionPublication of this article was funded by the Stellenbosch University Open Access Fund
dc.description.abstractENGLISH ABSTRACT: The lifetime of steam pipelines in long-term operation in coal-fired power plants are limited due to material damage that resulted from creep exposure. In the present study, the authors comparatively assess the damage of ex-service 12% Cr piping steel with varying degrees of exposure while using accelerated creep tests that employ digital image correlation (DIC) as well as microstructural investigation that is based on electron microscopy. The DIC technique, which allows multiple creep curves to be measured at temperatures ranging from 550–600 °C from a single specimen, revealed higher Zener–Hollomon parameters for a high damage material with a high void density when compared to a material with lower damage and lower void density. Both of the material states showed similar hardness values, subgrain sizes, and boundary character, despite the difference in void densities. Slightly higher inter-particle spacing of MX precipitates results in a lower threshold stress of 79 MPa for the high damage steel when compared to 97 MPa for the low damage material. Besides large Laves phase particles (>0.2 µm) that are found in the higher damaged materials that result in solid solution depletion, the most prominent microstructural damage indicator was a lower density of M₂₃C₆ precipitates. Therefore, the observations indicate that the Zener–Hollomon parameter and M₂₃C₆ particles are good damage assessment indicators between the most extreme damage states and they predict a lower damage level for a medium void density material.en_ZA
dc.description.urihttps://www.mdpi.com/1996-1944/12/19/3106
dc.description.versionPublisher's version
dc.format.extent31 pages
dc.identifier.citationVan Rooyen, M., et al. 2019. Creep damage assessment of ex-service 12% Cr power plant steel using digital image correlation and quantitative microstructural evaluation. Materials, 12(19):3106, doi:10.3390/ma12193106
dc.identifier.issn1996-1944 (online)
dc.identifier.otherdoi:10.3390/ma12193106
dc.identifier.urihttp://hdl.handle.net/10019.1/106525
dc.language.isoen_ZAen_ZA
dc.publisherMDPI
dc.rights.holderAuthors retain copyright
dc.subjectCreep damageen_ZA
dc.subjectCreep testing machinesen_ZA
dc.subjectPlants, Poweren_ZA
dc.subjectMicrostructure -- Evaluationen_ZA
dc.subjectSteelen_ZA
dc.subjectDigital image correlationen_ZA
dc.titleCreep damage assessment of ex-service 12% Cr power plant steel using digital image correlation and quantitative microstructural evaluationen_ZA
dc.typeArticleen_ZA
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