Microstructural evolution of 6063 aluminum during friction-stir welding

Yutaka S. Sato, Hiroyuki Kokawa, Masatoshi Enomoto, Shigetoshi Jogan

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668 Citations (Scopus)


The microstructural distribution associated with a hardness profile in a friction-stir-welded, agehardenable 6063 aluminum alloy has been characterized by transmission electron microscopy (TEM) and orientation imaging microscopy (OIM). The friction-stir process produces a softened region in the 6063 Al weld. Frictional heating and plastic flow during friction-stir welding create fine recrystallized grains in the weld zone and recovered grains in the thermomechanically affected zone. The hardness profile depends greatly on the precipitate distribution and only slightly on the grain size. The softened region is characterized by dissolution and growth of the precipitates during the welding. Simulated weld thermal cycles with different peak temperatures have shown that the precipitates are dissolved at temperatures higher than 675 K and that the density of the strengthening precipitate was reduced by thermal cycles lower than 675 K. A comparison between the thermal cycles and isothermal aging has suggested precipitation sequences in the softened region during friction-stir welding.

Original languageEnglish
Pages (from-to)2429-2437
Number of pages9
JournalMetallurgical and Materials Transactions A: Physical Metallurgy and Materials Science
Issue number9
Publication statusPublished - 1999

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Mechanics of Materials
  • Metals and Alloys


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