Keyhole behaviour during laser welding of zinc-coated steel

The production of consistent, high-quality laser welds on zinc-coated steels for the automotive industry remains a challenge. A simple overlap joint geometry is desirable in these applications but has been shown to be extremely detrimental to laser welding because the zinc vapour formed at the inter...

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Bibliographic Details
Published inJournal of physics. D, Applied physics Vol. 44; no. 4; p. 045502
Main Authors Pan, Y, Richardson, I M
Format Journal Article
LanguageEnglish
Published Bristol IOP Publishing 02.02.2011
Institute of Physics
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Summary:The production of consistent, high-quality laser welds on zinc-coated steels for the automotive industry remains a challenge. A simple overlap joint geometry is desirable in these applications but has been shown to be extremely detrimental to laser welding because the zinc vapour formed at the interface between the two sheets expands into the keyhole and disrupts fluid flow in the melt pool, which often leads to metal ejection. In this work, laser welding on sheets with various coating thicknesses has been performed and it is observed that the sheets with thick coatings (∼20 µm) show surprisingly good weldability. High speed video camera visualizations of the keyhole provide insight into the keyhole dynamics during the process. It appears that the dynamic pressure of zinc vapour can effectively elongate the keyhole and the process can reach a stable state when an elongated keyhole is continuously present. A simple analytical model has been developed to describe the influence of zinc vapour on keyhole elongation.
Bibliography:ObjectType-Article-2
SourceType-Scholarly Journals-1
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ISSN:0022-3727
1361-6463
DOI:10.1088/0022-3727/44/4/045502