Microstructural analysis of stir zone of Al alloy produced by friction stir spot welding

M. Fujimoto, S. Koga, N. Abe, Yutaka Sato, Hiroyuki Kokawa

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38 Citations (Scopus)


Friction stir spot welding (FSSW), which was recently developed as a spot joining technique, has been applied to a lap joint of Al alloy 6061 sheets, 1 mm in thickness, to clarify its microstructural features of the joint. A nugget shaped stir zone having finer grain size was observed around the exit hole of the probe. Crystallographic texture analyses using EBSD method suggested that the material flow occurred along the rotating direction of the FSSW tool in the wide region including the stir zone. In the periphery of the nugget shaped stir zone, which was characterised by finer grain size than the stir zone interior, no inclusions or precipitates were found on the SEM scale. A softened region was formed around the joint centre, which could be explained as resulting from dissolution and/or growth of the strengthening precipitates due to thermal cycle of FSSW.

Original languageEnglish
Pages (from-to)663-670
Number of pages8
JournalScience and Technology of Welding and Joining
Issue number7
Publication statusPublished - 2008 Oct 1


  • Aluminium alloy
  • Friction stir spot welding
  • Hardness
  • Material flow
  • Microstructure
  • Stir zone

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics


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