The Evolution of Abnormal Grains during the Heating Stage of a Post-Weld Solution Treatment in a Friction-Stir-Welded 2519 Aluminium Alloy

This work presents an in-depth investigation of the early stages of abnormal grain growth (AGG) in a friction-stir-welded (FSWed) 2519-T820 aluminium alloy. Microstructural evolutions, which occurred during the heating stage of a solution heat treatment (SHT), were studied. It was found that the wel...

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Bibliographic Details
Published in:Metals (Basel ) 2023-06, Vol.13 (6), p.1033
Main Authors: Zuiko, Ivan S., Malopheyev, Sergey, Rahimi, Salaheddin, Mironov, Sergey, Kaibyshev, Rustam
Format: Article
Language:English
Subjects:
abnormal grain growth (AGG)
Aging
Alloys
aluminium alloys
Aluminum
Aluminum base alloys
Annealing
Coarsening
Continuous casting
Evolution
Friction
Friction stir welding
friction-stir welding (FSW)
Grain boundaries
Grain growth
Grain structure
Heat treating
microstructure
Post-weld heat treatment
Precipitates
Scanning electron microscopy
secondary precipitates
Solution heat treatment
Specialty metals industry
Temperature
Temperature dependence
Thermal stability
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Summary:This work presents an in-depth investigation of the early stages of abnormal grain growth (AGG) in a friction-stir-welded (FSWed) 2519-T820 aluminium alloy. Microstructural evolutions, which occurred during the heating stage of a solution heat treatment (SHT), were studied. It was found that the welded materials underwent a complex sequence of precipitation phenomena, which eventually led to AGG. The evolution of precipitates was found to be heavily dependent on the FSW temperature condition. In a weld produced with a low-heat input, a significant portion of the precipitates were retained in the stir zone after FSW and then underwent coarsening and a subsequent dissolution during the annealing that followed. This led to a reduction in precipitation-pinning forces and thus promoted rapid grain coarsening. In a weld produced with a high-heat input, the initial precipitates were completely dissolved during the FSW, owing to the higher temperature, and then partially re-precipitated during the heating stage of the post-weld heat treatment. Due to the fine-grain structure of the stir zone, re-precipitation typically occurred at grain boundaries, thus promoting significant thermal stability. However, at temperatures approaching the SHT temperature, the new precipitates coarsened and then dissolved, resulting in AGG.
ISSN:2075-4701
2075-4701
DOI:10.3390/met13061033