Investigation of mechanical and microstructural properties of welded specimens of aa6061-t6 alloy with friction stir welding and parallel-friction stir welding methods

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Issue Date
2021-10-12
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Authors
Ghiasvand, Amir
Yavari, Mohammad Mahdi
Tomków, Jacek
Grimaldo Guerrero, John William
Kheradmandan, Hasan
Dorofeev, Aleskei
Memon, Shabbir
Aghajani Derazkola, Hesamoddin
Advisor
Citation

Ghiasvand, A., Yavari, M. M., Tomków, J., Guerrero, J. W. G., Kheradmandan, H., Dorofeev, A., . . . Derazkola, H. A. (2021). Investigation of mechanical and microstructural properties of welded specimens of aa6061-t6 alloy with friction stir welding and parallel-friction stir welding methods. Materials, 14(20) doi:10.3390/ma14206003

Abstract

The present study investigates the effect of two parameters of process type and tool offset on tensile, microhardness, and microstructure properties of AA6061-T6 aluminum alloy joints. Three methods of Friction Stir Welding (FSW), Advancing Parallel-Friction Stir Welding (AP-FSW), and Retreating Parallel-Friction Stir Welding (RP-FSW) were used. In addition, four modes of 0.5, 1, 1.5, and 2 mm of tool offset were used in two welding passes in AP-FSW and RP-FSW processes. Based on the results, it was found that the mechanical properties of welded specimens with AP-FSW and RP-FSW techniques experience significant increments compared to FSW specimens. The best mechanical and microstructural properties were observed in the samples welded by RP-FSW, AP-FSW, and FSW methods, respectively. Welded specimens with the RP-FSW technique had better mechanical properties than other specimens due to the concentration of material flow in the weld nugget and proper microstructure refinement. In both AP-FSW and RP-FSW processes, by increasing the tool offset to 1.5 mm, joint efficiency increased significantly. The highest weld strength was found for welded specimens by RP-FSW and AP-FSW processes with a 1.5 mm tool offset. The peak sample of the RP-FSW process (1.5 mm offset) had the closest mechanical properties to the base metal, in which the Yield Stress (YS), ultimate tensile strength (UTS), and elongation percentage (E%) were 76.4%, 86.5%, and 70% of base metal, respectively. In the welding area, RP-FSW specimens had smaller average grain size and higher hardness values than AP-FSW specimens.

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Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).
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