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Analysis of different methods for the prevention of pore formation in keyhole laser spot welding
Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.ORCID iD: 0000-0002-3569-6795
Joining and Welding Research Institute, Osaka University.
Joining and Welding Research Institute, Osaka University.
2002 (English)In: Advanced processes and technologies in welding and allied processes: IIW International conference ; 24 - 25 June 2002, Copenhagen, Denmark / [ed] Jens Klæstrup Kristensen, Roissy: International Institute of welding , 2002, p. 39-50Conference paper, Published paper (Refereed)
Abstract [en]

Pore formation in keyhole Nd:YAG-laser spot welding has been investigated experimentally and theoretically. High speed X-ray imaging of the process delivers the shape of the keyhole just before switching off the laser beam. Starting from this shape the keyhole collapse is calculated by the aid of a mathematical model, distinguishing various physical phases of differing time scales, i.e. post-vaporisation, cooling, relaxation flushing of the excess vapour, and surface tension driven collapse of the keyhole along with vapour and melt flow. In case of a bottleneck-shaped keyhole, which is likely to form due to the paradox of flow inversion, necking forms a cavity, thus trapping vapour. According to X-ray observation and numerical simulation a contracting bubble forms that rises and is finally trapped by re-solidification of the melt, thus forming a pore. Different strategies for the prevention of pores are discussed, namely pulse-tail shaping for controlled keyhole contraction, welding under low ambient pressure which rarefies the keyhole vapour, and proper choice of the process parameters like spot size, pulse duration and shielding gas pressure for avoiding a bottleneck-shaped keyhole

Place, publisher, year, edition, pages
Roissy: International Institute of welding , 2002. p. 39-50
Series
Welding in the World, ISSN 0043-2288 ; 46(2002)
National Category
Manufacturing, Surface and Joining Technology
Research subject
Manufacturing Systems Engineering
Identifiers
URN: urn:nbn:se:ltu:diva-31819Local ID: 61d83470-f256-11db-bb1b-000ea68e967bOAI: oai:DiVA.org:ltu-31819DiVA, id: diva2:1005053
Conference
International Conference Advanced Processes and Technologies in Welding and Allied Processes : 24/06/2002 - 25/06/2002
Note
Godkänd; 2002; 20070424 (cira)Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2017-11-25Bibliographically approved

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CiteExportLink to record
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Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
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Language
  • de-DE
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  • en-US
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Output format
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