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Physical Verification of the Melt Pool in Laser-Bed Fusion / Andre Giordimaina

Swansea University Author: Andre Giordimaina

DOI (Published version): 10.23889/Suthesis.49707

Abstract

Laser Powder-Bed Fusion (LPBF) is an additive manufacturing process which fuses metal powder on a layer by layer basis to form complex three-dimensional components. As with other additive processes, LPBF is seeing a rapid evolution of machine design, scanning techniques, and materials development wh...

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Published: Swansea 2017
Institution: Swansea University
Degree level: Doctoral
Degree name: EngD
URI: https://cronfa.swan.ac.uk/Record/cronfa49707
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fullrecord <?xml version="1.0"?><rfc1807><datestamp>2022-12-18T10:02:55.9931033</datestamp><bib-version>v2</bib-version><id>49707</id><entry>2019-03-25</entry><title>Physical Verification of the Melt Pool in Laser-Bed Fusion</title><swanseaauthors><author><sid>9e9b931890d50415c5abc8fba674344c</sid><firstname>Andre</firstname><surname>Giordimaina</surname><name>Andre Giordimaina</name><active>true</active><ethesisStudent>false</ethesisStudent></author></swanseaauthors><date>2019-03-25</date><deptcode>EEN</deptcode><abstract>Laser Powder-Bed Fusion (LPBF) is an additive manufacturing process which fuses metal powder on a layer by layer basis to form complex three-dimensional components. As with other additive processes, LPBF is seeing a rapid evolution of machine design, scanning techniques, and materials development which has moved the process well beyond its origins in rapid prototyping to a process which can manufacture fit-for-purpose components. At the heart of the LPBF process lies the melt pool, and the way in which the laser properties, such as speed, power and beam diameter interact to form tracks fused to the substrate is integral to the way in which multiple tracks will fill the contours across each layer in the build sequence. Controlling the as-solidified bead shape is important to ensure optimal mechanical properties. A widespread technique for measuring the effect of laser properties on the mechanical properties and track formation is process mapping. Single-layer or single-track process maps, which measure the behaviour of the melt according to laser properties on a single layer of powder, have been limited to a base plate of same composition, but with a different microstructure, typically resulting from a rolling process. The work in this thesis describes the efforts to standardise a high-throughput method of creating process maps which measure the effects of these process parameters on, in a way which compliments and improves upon the usual technique of deposition of single line tracks directly onto a base plate. One result of this work is a new method where substrates are built using the LPBF process, on which single tracks are deposited with a controlled powder depth. This is done in such a way that the as-built tracks are representative of the process at regions away from the base plate, by building the substrate in-situ, before the forming of the tracks. It was found that the crucible single track method could be used quite effectively to control the powder layer depth at which tracks were deposited on. The additional benefit granted by the crucible substrate was the ease at which high quality topographical and cross-sectional metallography could take place in order to quantify and investigate the effects of changing the parameters. For example, by using the crucible method, it was found that titanium alloy Ti-6Al-4V, at a maximum laser power of 200W, could form relatively stable track formations at 100&#xB5;m layer thickness at a scan speed of 500mms-1. At lower power values, faster scan speeds or larger layer depths, tracks would not form successfully. Another important outcome was that the crucible method predicted a much less severe transition between conductive and keyhole modes of melting than direct deposition of single tracks onto a baseplate, with shallower re-melting of lower layers. The crucible method also predicted a more forgiving transition between continuous lines and lines which had broken down due to poor wetting or insufficient temperatures.</abstract><type>E-Thesis</type><journal/><volume/><journalNumber/><paginationStart/><paginationEnd/><publisher/><placeOfPublication>Swansea</placeOfPublication><isbnPrint/><isbnElectronic/><issnPrint/><issnElectronic/><keywords>Additive Manufacturing, Laser Powder-Bed Fusion, Keyholing, Balling</keywords><publishedDay>31</publishedDay><publishedMonth>12</publishedMonth><publishedYear>2017</publishedYear><publishedDate>2017-12-31</publishedDate><doi>10.23889/Suthesis.49707</doi><url/><notes>A selection of third party content is redacted or is partially redacted from this thesis.</notes><college>COLLEGE NANME</college><department>Engineering</department><CollegeCode>COLLEGE CODE</CollegeCode><DepartmentCode>EEN</DepartmentCode><institution>Swansea University</institution><degreelevel>Doctoral</degreelevel><degreename>EngD</degreename><apcterm/><funders/><projectreference/><lastEdited>2022-12-18T10:02:55.9931033</lastEdited><Created>2019-03-25T15:59:17.5470032</Created><path><level id="1">Faculty of Science and Engineering</level><level id="2">School of Engineering and Applied Sciences - Uncategorised</level></path><authors><author><firstname>Andre</firstname><surname>Giordimaina</surname><order>1</order></author></authors><documents><document><filename>0049707-25032019160122.pdf</filename><originalFilename>Giordimaina_Andre_EngD_Thesis_Final_Redactedv2.pdf</originalFilename><uploaded>2019-03-25T16:01:22.8670000</uploaded><type>Output</type><contentLength>18035683</contentLength><contentType>application/pdf</contentType><version>Redacted version - open access</version><cronfaStatus>true</cronfaStatus><embargoDate>2019-03-24T00:00:00.0000000</embargoDate><copyrightCorrect>true</copyrightCorrect></document></documents><OutputDurs/></rfc1807>
spelling 2022-12-18T10:02:55.9931033 v2 49707 2019-03-25 Physical Verification of the Melt Pool in Laser-Bed Fusion 9e9b931890d50415c5abc8fba674344c Andre Giordimaina Andre Giordimaina true false 2019-03-25 EEN Laser Powder-Bed Fusion (LPBF) is an additive manufacturing process which fuses metal powder on a layer by layer basis to form complex three-dimensional components. As with other additive processes, LPBF is seeing a rapid evolution of machine design, scanning techniques, and materials development which has moved the process well beyond its origins in rapid prototyping to a process which can manufacture fit-for-purpose components. At the heart of the LPBF process lies the melt pool, and the way in which the laser properties, such as speed, power and beam diameter interact to form tracks fused to the substrate is integral to the way in which multiple tracks will fill the contours across each layer in the build sequence. Controlling the as-solidified bead shape is important to ensure optimal mechanical properties. A widespread technique for measuring the effect of laser properties on the mechanical properties and track formation is process mapping. Single-layer or single-track process maps, which measure the behaviour of the melt according to laser properties on a single layer of powder, have been limited to a base plate of same composition, but with a different microstructure, typically resulting from a rolling process. The work in this thesis describes the efforts to standardise a high-throughput method of creating process maps which measure the effects of these process parameters on, in a way which compliments and improves upon the usual technique of deposition of single line tracks directly onto a base plate. One result of this work is a new method where substrates are built using the LPBF process, on which single tracks are deposited with a controlled powder depth. This is done in such a way that the as-built tracks are representative of the process at regions away from the base plate, by building the substrate in-situ, before the forming of the tracks. It was found that the crucible single track method could be used quite effectively to control the powder layer depth at which tracks were deposited on. The additional benefit granted by the crucible substrate was the ease at which high quality topographical and cross-sectional metallography could take place in order to quantify and investigate the effects of changing the parameters. For example, by using the crucible method, it was found that titanium alloy Ti-6Al-4V, at a maximum laser power of 200W, could form relatively stable track formations at 100µm layer thickness at a scan speed of 500mms-1. At lower power values, faster scan speeds or larger layer depths, tracks would not form successfully. Another important outcome was that the crucible method predicted a much less severe transition between conductive and keyhole modes of melting than direct deposition of single tracks onto a baseplate, with shallower re-melting of lower layers. The crucible method also predicted a more forgiving transition between continuous lines and lines which had broken down due to poor wetting or insufficient temperatures. E-Thesis Swansea Additive Manufacturing, Laser Powder-Bed Fusion, Keyholing, Balling 31 12 2017 2017-12-31 10.23889/Suthesis.49707 A selection of third party content is redacted or is partially redacted from this thesis. COLLEGE NANME Engineering COLLEGE CODE EEN Swansea University Doctoral EngD 2022-12-18T10:02:55.9931033 2019-03-25T15:59:17.5470032 Faculty of Science and Engineering School of Engineering and Applied Sciences - Uncategorised Andre Giordimaina 1 0049707-25032019160122.pdf Giordimaina_Andre_EngD_Thesis_Final_Redactedv2.pdf 2019-03-25T16:01:22.8670000 Output 18035683 application/pdf Redacted version - open access true 2019-03-24T00:00:00.0000000 true
title Physical Verification of the Melt Pool in Laser-Bed Fusion
spellingShingle Physical Verification of the Melt Pool in Laser-Bed Fusion
Andre Giordimaina
title_short Physical Verification of the Melt Pool in Laser-Bed Fusion
title_full Physical Verification of the Melt Pool in Laser-Bed Fusion
title_fullStr Physical Verification of the Melt Pool in Laser-Bed Fusion
title_full_unstemmed Physical Verification of the Melt Pool in Laser-Bed Fusion
title_sort Physical Verification of the Melt Pool in Laser-Bed Fusion
author_id_str_mv 9e9b931890d50415c5abc8fba674344c
author_id_fullname_str_mv 9e9b931890d50415c5abc8fba674344c_***_Andre Giordimaina
author Andre Giordimaina
author2 Andre Giordimaina
format E-Thesis
publishDate 2017
institution Swansea University
doi_str_mv 10.23889/Suthesis.49707
college_str Faculty of Science and Engineering
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hierarchy_top_id facultyofscienceandengineering
hierarchy_top_title Faculty of Science and Engineering
hierarchy_parent_id facultyofscienceandengineering
hierarchy_parent_title Faculty of Science and Engineering
department_str School of Engineering and Applied Sciences - Uncategorised{{{_:::_}}}Faculty of Science and Engineering{{{_:::_}}}School of Engineering and Applied Sciences - Uncategorised
document_store_str 1
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description Laser Powder-Bed Fusion (LPBF) is an additive manufacturing process which fuses metal powder on a layer by layer basis to form complex three-dimensional components. As with other additive processes, LPBF is seeing a rapid evolution of machine design, scanning techniques, and materials development which has moved the process well beyond its origins in rapid prototyping to a process which can manufacture fit-for-purpose components. At the heart of the LPBF process lies the melt pool, and the way in which the laser properties, such as speed, power and beam diameter interact to form tracks fused to the substrate is integral to the way in which multiple tracks will fill the contours across each layer in the build sequence. Controlling the as-solidified bead shape is important to ensure optimal mechanical properties. A widespread technique for measuring the effect of laser properties on the mechanical properties and track formation is process mapping. Single-layer or single-track process maps, which measure the behaviour of the melt according to laser properties on a single layer of powder, have been limited to a base plate of same composition, but with a different microstructure, typically resulting from a rolling process. The work in this thesis describes the efforts to standardise a high-throughput method of creating process maps which measure the effects of these process parameters on, in a way which compliments and improves upon the usual technique of deposition of single line tracks directly onto a base plate. One result of this work is a new method where substrates are built using the LPBF process, on which single tracks are deposited with a controlled powder depth. This is done in such a way that the as-built tracks are representative of the process at regions away from the base plate, by building the substrate in-situ, before the forming of the tracks. It was found that the crucible single track method could be used quite effectively to control the powder layer depth at which tracks were deposited on. The additional benefit granted by the crucible substrate was the ease at which high quality topographical and cross-sectional metallography could take place in order to quantify and investigate the effects of changing the parameters. For example, by using the crucible method, it was found that titanium alloy Ti-6Al-4V, at a maximum laser power of 200W, could form relatively stable track formations at 100µm layer thickness at a scan speed of 500mms-1. At lower power values, faster scan speeds or larger layer depths, tracks would not form successfully. Another important outcome was that the crucible method predicted a much less severe transition between conductive and keyhole modes of melting than direct deposition of single tracks onto a baseplate, with shallower re-melting of lower layers. The crucible method also predicted a more forgiving transition between continuous lines and lines which had broken down due to poor wetting or insufficient temperatures.
published_date 2017-12-31T04:00:54Z
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score 11.01628

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