Analysis of plastic flow of the Al alloy joint produced by friction stir spot welding

Mitsuo Fujimoto, Shinji Koga, Natsumi Abe, S. Yutaka Sato, Hiroyuki Kokawa

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)


This study examined development of the stir zone and plastic flow of the material during friction stir spot joining of aluminium alloys. The development of the stir zone was discussed through the observation of macro sections of the joints produced at various process times. The friction stir spot joining trial with insert of Au foil to lap surface and the dissimilar lap friction stir spot joining showed that the movement of the lap surface was attributed to the downward plastic flow from the upper plate to the lower plate around the probe. Additionally, it was clarified that the direction of the plastic flow was roughly the same as the direction of the tool rotation. The dissimilar butt friction stir spot joining suggested that the plastic flow occurred not only within the stir zone but also in a larger area below the tool shoulder. The present study revealed that the threads on the probe surface were important for producing the plastic flow of thickness direction during friction stir spot joining.

Original languageEnglish
Pages (from-to)589-596
Number of pages8
JournalWelding International
Issue number8
Publication statusPublished - 2009
Externally publishedYes


  • Aluminium alloy
  • Friction stir spot welding
  • Insert material
  • Plastic flow
  • Stir zone
  • Thread

ASJC Scopus subject areas

  • Mechanics of Materials
  • Mechanical Engineering
  • Metals and Alloys


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