Microstructural issues in a friction-stir-welded aluminum alloy

Journal Article · Tue Feb 03 04:00:00 EST 1998 · Scripta Materialia

DOI:https://doi.org/10.1016/S1359-6462(97)00551-4· OSTI ID:605669

Flores, O V; Kennedy, C; Murr, L E; Brown, D; Pappu, S; Nowak, B M; McClure, J C ^[1]

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1. Univ. of Texas, El Paso, TX (United States)

Recent observations of microstructures associated with friction-stir welding (FSW) in a number of aluminum alloys have consistently demonstrated the actual weld zone to consist of a (dynamically) recrystallized grain structure resulting from the extreme, solid-state, plastic deformation characterizing the process. Because of solubilities associated with the various precipitates in 7075 and 6061 aluminum alloys, and the fact that the precipitates were either homogeneously distributed throughout both the original (unwelded) work-piece plates and the well zones (or formed varying densities of Widmanstaetten patterns within the original and recrystallized grains), it has been difficult to follow the stirring of stable, second-phase particles from the base metal (work-piece) into the weld zone. In the present investigation, a compositionally modified 1100 aluminum alloy (nominally 99.2% Al, 0.5% Fe, 0.15% Cu, 0.12% Si, 0.05 Mn, 0.04 Ti, balance in weight percent of Be and Mg), forming a stable microdendritic (second-phase), equiaxed, cell structure was friction-stir welded. These thermally stable, geometrically specific, precipitates in the base metal were compared with their disposition within the friction-stir-weld zone. In addition, as-cast plates of this alloy were cold-rolled 50% and friction-stir-welded in order to compare these two schedules (as-cast and 50% cold-rolled) in terms of residual hardness variations and related microstructural issues as well as the effect of prior deformation on the friction-stir welding process.

• Sponsoring Organization: National Aeronautics and Space Administration, Washington, DC (United States); Consejo Nacional de Ciencia y Tecnologia (CONACYT), Mexico City (Mexico)
• OSTI ID: 605669
• Journal Information: Scripta Materialia, Journal Name: Scripta Materialia Journal Issue: 5 Vol. 38; ISSN 1359-6462; ISSN SCMAF7
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM BASE ALLOYS
COLD WORKING
HARDNESS
MICROSTRUCTURE
RECRYSTALLIZATION
WELDING