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Investigation of porosity formation in additively manufactured AlSi10Mg samples using X-ray micro-computed tomography and X-ray interferometry
Thesis (MSc)--Stellenbosch University, 2025.
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Stellenbosch : Stellenbosch University
2025
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| _version_ | 1867614028492177408 |
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| access_status_str | Open Access |
| author | Mbuyisa, Busisiwe |
| author2 | Du Plessis, Anton |
| author_browse | Du Plessis, Anton Mbuyisa, Busisiwe |
| author_facet | Du Plessis, Anton Mbuyisa, Busisiwe |
| author_sort | Mbuyisa, Busisiwe |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MSc)--Stellenbosch University, 2025. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/132621 |
| institution | Stellenbosch University (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:45:31.220Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2025 |
| publishDateRange | 2025 |
| publishDateSort | 2025 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/132621 Investigation of porosity formation in additively manufactured AlSi10Mg samples using X-ray micro-computed tomography and X-ray interferometry Mbuyisa, Busisiwe Du Plessis, Anton Steenkamp, Christine M. Stellenbosch University. Faculty of Science. Dept. of Physics. Additive manufacturing -- Materials Laser powder bed fusion -- Technological innovations Microcomputed tomography Talbot Lau interferometer Three-dimensional imaging Porosity -- Measurement Nondestructive testing -- Data processing UCTD Thesis (MSc)--Stellenbosch University, 2025. Mbuyisa, B. 2025. Investigation of porosity formation in additively manufactured AlSi10Mg samples using X-ray micro-computed tomography and X-ray interferometry. Unpublished masters thesis. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/bbca5c3a-8083-4f57-b5e7-7db832180630 ENGLISH ABSTRACT: Additive manufacturing (AM) is a process in which a three-dimensional (3D) digital model is used to build up components by adding materials in a layer-by-layer mode. Laser powder bed fusion (L-PBF) is one of the AM process categories. It is based on the use of laser as a thermal energy source to selectively melt powder materials. This technique is highly effective in manufacturing objects of complex and custom geometries, as well as joining different parts of components into one functional product. Moreover, it enables the production of reliable and high-quality 3D parts. This makes its application suitable for industries such as aerospace, medical and automotive industries, among others. However, defects such as porosities negatively affect mechanical properties of the material parts and hence affect the application of this process in industries. X-ray micro-computed tomography (micro-CT) is widely known as a reliable non-destructive test (NDT) method. This method enables the ability to see inside objects without having to physically cut them. It has been used widely for the past few decades, especially for quantification of porosity. An X-ray based Talbot Lau interferometer (TLI) imaging setup is based on the principle of using gratings for extraction of absorption, phase contrast and darkfield information simultaneously. Phase contrast depends on refraction, and it is useful for contrast enhancement in lightweight materials. Darkfield depends on the scattering of X-rays due to differences in material density, and it could be useful for identifying porosity in lightweight materials. In this study, three batches of AlSi₁₀Mg cylinder samples with 9 mm diameter and 10 mm height were printed with L-PBF method. These samples were printed at various laser scanning speeds in sets of fixed laser power settings (250 W and 400 W). A micro-CT system was used to perform two-minute scans with the purpose of determining the most porous samples. The selected samples were then scanned in high resolution (approximately 39 minutes per scan). The micro-CT higher resolution porosity quantification results were used to study the relationship between L-PBF process parameters and porosity formation. The selected samples were also scanned using a TLI system. The aim of this work was to investigate the relationship between porosity formation and L-PBF process parameters in AlSi10Mg samples, and to determine the possibility of using a TLI system as an alternative NDT tool. For samples of 250 W, the trend of micro-CT results for porosity percentage indicated that laser scanning speed between 1000-1400 mm/s is optimal to minimize porosity. For samples of 400 W, the minimum porosity percentage was not achieved, the porosity trend results indicated that minimum porosity might be achieved at higher scanning speed than the maximum speed that was available for this power in the experiment. The TLI results indicated that the samples were highly porous, correlating with the micro-CT porosity results. This study concludes that this TLI system could be used as an alternative NDT tool for qualitative purposes in L-PBF AlSi₁₀Mg parts. AFRIKAANSE OPSOMMING: Additiewe vervaardiging (AM) is 'n proses waarin 'n driedimensionele (3D) digitale model gebruik word om komponente op te bou deur materiale in 'n laag-vir-laag-modus by te voeg. Laserpoeierbedsfusie (L-PBF) is een van die AM-proseskategorieë. Dit is gebaseer op die gebruik van ‘n laser as 'n termiese energiebron om poeiermateriaal selektief te smelt. Hierdie tegniek is hoogs effektief in die vervaardiging van voorwerpe met komplekse en pasgemaakte geometrieë, sowel as om verskillende dele van komponente in een funksionele produk te verbind. Boonop maak dit die vervaardiging van betroubare en hoë gehalte 3D-onderdele moontlik. Dit maak die toepassing daarvan geskik vir nywerhede soos onder meer lugvaart-, mediese en motorindustrieë. Defekte soos porositeit beïnvloed egter meganiese eienskappe van die materiaaldele negatief en beïnvloed dus die toepassing van hierdie proses in nywerhede. X-straal mikro-rekenaartomografie (mikro-CT) is wyd bekend as 'n betroubare nie-vernietigende toets (NVT) metode. Hierdie metode maak dit moontlik om binne-in voorwerpe te sien sonder om dit fisies te sny. Dit is vir die afgelope paar dekades algemeen gebruik, veral vir die kwantifisering van porositeit. 'n X-straal-gebaseerde Talbot Lau interferometer (TLI) afbeeldingsopstelling is gebaseer op die beginsel van die gebruik van roosters, en maak dit moontlik om absorpsie-, fasekontras- en donkerveldafbeelding gelyktydig uit die metings te verkry. Fasekontras afbeelding hang af van breking, en dit is nuttig vir kontrasverbetering in liggewig materiale. Donkerveld afbeelding is afhanklik van die verstrooiing van X-strale as gevolg van verskille in materiaaldigtheid, en dit kan nuttig wees vir die identifisering van porositeit in materiale met lae atoommassa. In hierdie studie is drie groepe AlSi₁₀Mg silinders met 9 mm deursnee en 10 mm hoogte gedruk met die L-PBF metode. Hierdie monsters is teen verskeie laserskanderingsspoed gedruk, in twee stelle met verskillende vaste laserdrywing (250 W en 400 W). ’n Mikro-CT-stelsel is gebruik om twee-minuut skanderings uit te voer met die doel om die mees poreuse monsters te bepaal. Die geselekteerde monsters is dan in hoë resolusie (ongeveer 39 minute per skandering) geskandeer. Die porositeit resultate van die hoër resolusie mikro-CT skanderings is gebruik om die verband tussen die L-PBF proses parameters en porositeitvorming te bestudeer. Die geselekteerde monsters is ook met behulp van 'n TLI-stelsel geskandeer. Die doel van hierdie werk was om die moontlikheid te bepaal om 'n TLI-stelsel as 'n alternatiewe NVT-instrument te gebruik. Vir monsters van 250 W het die mikro-CT-resultate vir porositeitspersentasie getoon dat ‘n laserskanderingspoed tussen 1000-1400 mm/s optimaal is om porositeit te minimaliseer. Vir monsters van 400 W is die minimum porositeit persentasie nie bereik nie, en die tendens van die resultate het aangedui dat minimum porositeit bereik kan word teen hoër skanderingspoed vir hierdie drywing a wat beskikbaar was in die eksperiment. Die TLI-resultate het aangedui dat die monsters hoogs poreus was, wat ooreenstem met die mikro-CT-porositeitsresultate. Hierdie studie kom tot die gevolgtrekking dat hierdie TLI-stelsel gebruik kan word as 'n alternatiewe NVT hulpmiddel vir kwalitatiewe doeleindes in L-PBF AlSi₁₀Mg dele. Masters 2025-06-12T06:06:57Z 2025-06-12T06:06:57Z 2025-03 Thesis https://scholar.sun.ac.za/handle/10019.1/132621 en Stellenbosch University 253 pages : illustrations application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Additive manufacturing -- Materials Laser powder bed fusion -- Technological innovations Microcomputed tomography Talbot Lau interferometer Three-dimensional imaging Porosity -- Measurement Nondestructive testing -- Data processing UCTD Mbuyisa, Busisiwe Investigation of porosity formation in additively manufactured AlSi10Mg samples using X-ray micro-computed tomography and X-ray interferometry |
| title | Investigation of porosity formation in additively manufactured AlSi10Mg samples using X-ray micro-computed tomography and X-ray interferometry |
| title_full | Investigation of porosity formation in additively manufactured AlSi10Mg samples using X-ray micro-computed tomography and X-ray interferometry |
| title_fullStr | Investigation of porosity formation in additively manufactured AlSi10Mg samples using X-ray micro-computed tomography and X-ray interferometry |
| title_full_unstemmed | Investigation of porosity formation in additively manufactured AlSi10Mg samples using X-ray micro-computed tomography and X-ray interferometry |
| title_short | Investigation of porosity formation in additively manufactured AlSi10Mg samples using X-ray micro-computed tomography and X-ray interferometry |
| title_sort | investigation of porosity formation in additively manufactured alsi10mg samples using x ray micro computed tomography and x ray interferometry |
| topic | Additive manufacturing -- Materials Laser powder bed fusion -- Technological innovations Microcomputed tomography Talbot Lau interferometer Three-dimensional imaging Porosity -- Measurement Nondestructive testing -- Data processing UCTD |
| url | https://scholar.sun.ac.za/handle/10019.1/132621 |
| work_keys_str_mv | AT mbuyisabusisiwe investigationofporosityformationinadditivelymanufacturedalsi10mgsamplesusingxraymicrocomputedtomographyandxrayinterferometry |