A sub-structural analysis of friction stir welded joints in an AA6056 Al-alloy in T4 and T6 temper conditions

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Vol. 454; pp. 52 - 62
• Main Authors: Olea, C.A.W., Roldo, L., dos Santos, J.F., Strohaecker, T.R.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 25.04.2007; Elsevier
• Subjects: Applied sciences; Exact sciences and technology; Friction stir welding; Joining, thermal cutting: metallurgical aspects; Metals. Metallurgy; Precipitation; Recrystallization; Sub-structure; Welding; Sub-structure; Precipitation; Friction stir welding; Recrystallization; Heat treatment; Dislocation structure; Equiaxed structure; Aluminium alloy; Precipitate; Substructure; Transmission electron microscopy; Tempering; Microstructure; Weld zone; Structural analysis
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2006.12.055

Friction stir welds in an Al-alloy AA6056 in T4 and T6 temper were investigated in terms of grain structure, dislocation density and second phase particles at the different zones of the welded joint. These results were subsequently compared with the unaffected base material. The aim of this investigation was to understand the metallurgical phenomena controlling the microstructural evolution associated with the friction stir weld process for temper condition. Major emphasis was placed on the evaluation of second phase particle formation and evolution at weld zones. The stir zone of the T4 temper maintains the precipitation features of the base material, while for the T6 temper, dissolution of thin precipitates occurs. The stir zone of post weld heat treated joints presented equiaxed grains fully covered of very thin precipitates randomly distributed along the matrix. These precipitates are about 2–10 nm in diameter. The remaining regions are characterised by partial dissolution and precipitate coarsening during the FSW process.