Microstructure and mechanical properties of refill friction stir spot welded joints: Effects of tool size and welding parameters

A novel refill friction stir spot welding (RFSSW) technique employing large-sized tools is proposed. The microstructure and mechanical properties of joints produced with a large-sized welding tool and a conventional tool are compared. The results show that the exit line resulting from the sleeve bec...

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Main Authors: Yangfan Zou, Wenya Li, Xiawei Yang, Yu Su, Qiang Chu, Zhikang Shen
Format: Article
Language:English
Published: Elsevier 2022-11-01
Series:Journal of Materials Research and Technology
Subjects:
Online Access:http://www.sciencedirect.com/science/article/pii/S2238785422018130
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author Yangfan Zou
Wenya Li
Xiawei Yang
Yu Su
Qiang Chu
Zhikang Shen
author_facet Yangfan Zou
Wenya Li
Xiawei Yang
Yu Su
Qiang Chu
Zhikang Shen
author_sort Yangfan Zou
collection DOAJ
description A novel refill friction stir spot welding (RFSSW) technique employing large-sized tools is proposed. The microstructure and mechanical properties of joints produced with a large-sized welding tool and a conventional tool are compared. The results show that the exit line resulting from the sleeve becomes longer with increasing the plunge depth, and the diameter of nugget increases with higher rotational speed for the joints produced by both conventional and novel tools. The plunge depth increases from 2.0 mm to 2.2 mm, then to 2.4 mm, which affects the hook defect to bend upwards, almost parallel to the lap interface, to bend downwards, respectively. The joints produced with the novel tool have a flat hook compared to the conventional tool. The microstructure evolution of the conventional and novel joints is similar. The tensile-shear and tearing forces measured of the novel joints are higher than those of the conventional joints for the same welding parameters. For conventional joints, the maximum tensile-shear and tearing forces are 8.6 ± 0.1 kN and 4.4 ± 0.2 kN, respectively. The maximum tensile-shear and tearing forces for novel joints are 10.9 ± 0.1 kN and 5.6 ± 0.1 kN, respectively. After the tensile-shear test, there are three modes of fracture, the upper-mixed, the lower-mixed, and the shear fracture one. The plunge depth has a pronounced effect on the fracture mode of joints.
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spelling doaj.art-45983a45cbc34262b94e35cc0290ac492022-12-22T04:23:15ZengElsevierJournal of Materials Research and Technology2238-78542022-11-012150665080Microstructure and mechanical properties of refill friction stir spot welded joints: Effects of tool size and welding parametersYangfan Zou0Wenya Li1Xiawei Yang2Yu Su3Qiang Chu4Zhikang Shen5State Key Laboratory of Solidification Processing, Shaanxi Key Laboratory of Friction Welding Technologies, Northwestern Polytechnical University, Xi'an 710072, Shaanxi, PR ChinaCorresponding author.; State Key Laboratory of Solidification Processing, Shaanxi Key Laboratory of Friction Welding Technologies, Northwestern Polytechnical University, Xi'an 710072, Shaanxi, PR ChinaCorresponding author.; State Key Laboratory of Solidification Processing, Shaanxi Key Laboratory of Friction Welding Technologies, Northwestern Polytechnical University, Xi'an 710072, Shaanxi, PR ChinaState Key Laboratory of Solidification Processing, Shaanxi Key Laboratory of Friction Welding Technologies, Northwestern Polytechnical University, Xi'an 710072, Shaanxi, PR ChinaState Key Laboratory of Solidification Processing, Shaanxi Key Laboratory of Friction Welding Technologies, Northwestern Polytechnical University, Xi'an 710072, Shaanxi, PR ChinaState Key Laboratory of Solidification Processing, Shaanxi Key Laboratory of Friction Welding Technologies, Northwestern Polytechnical University, Xi'an 710072, Shaanxi, PR ChinaA novel refill friction stir spot welding (RFSSW) technique employing large-sized tools is proposed. The microstructure and mechanical properties of joints produced with a large-sized welding tool and a conventional tool are compared. The results show that the exit line resulting from the sleeve becomes longer with increasing the plunge depth, and the diameter of nugget increases with higher rotational speed for the joints produced by both conventional and novel tools. The plunge depth increases from 2.0 mm to 2.2 mm, then to 2.4 mm, which affects the hook defect to bend upwards, almost parallel to the lap interface, to bend downwards, respectively. The joints produced with the novel tool have a flat hook compared to the conventional tool. The microstructure evolution of the conventional and novel joints is similar. The tensile-shear and tearing forces measured of the novel joints are higher than those of the conventional joints for the same welding parameters. For conventional joints, the maximum tensile-shear and tearing forces are 8.6 ± 0.1 kN and 4.4 ± 0.2 kN, respectively. The maximum tensile-shear and tearing forces for novel joints are 10.9 ± 0.1 kN and 5.6 ± 0.1 kN, respectively. After the tensile-shear test, there are three modes of fracture, the upper-mixed, the lower-mixed, and the shear fracture one. The plunge depth has a pronounced effect on the fracture mode of joints.http://www.sciencedirect.com/science/article/pii/S2238785422018130Refill friction stir spot welding6061 aluminum alloyWelding toolMicrostructureMechanical properties
spellingShingle Yangfan Zou
Wenya Li
Xiawei Yang
Yu Su
Qiang Chu
Zhikang Shen
Microstructure and mechanical properties of refill friction stir spot welded joints: Effects of tool size and welding parameters
Journal of Materials Research and Technology
Refill friction stir spot welding
6061 aluminum alloy
Welding tool
Microstructure
Mechanical properties
title Microstructure and mechanical properties of refill friction stir spot welded joints: Effects of tool size and welding parameters
title_full Microstructure and mechanical properties of refill friction stir spot welded joints: Effects of tool size and welding parameters
title_fullStr Microstructure and mechanical properties of refill friction stir spot welded joints: Effects of tool size and welding parameters
title_full_unstemmed Microstructure and mechanical properties of refill friction stir spot welded joints: Effects of tool size and welding parameters
title_short Microstructure and mechanical properties of refill friction stir spot welded joints: Effects of tool size and welding parameters
title_sort microstructure and mechanical properties of refill friction stir spot welded joints effects of tool size and welding parameters
topic Refill friction stir spot welding
6061 aluminum alloy
Welding tool
Microstructure
Mechanical properties
url http://www.sciencedirect.com/science/article/pii/S2238785422018130
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AT zhikangshen microstructureandmechanicalpropertiesofrefillfrictionstirspotweldedjointseffectsoftoolsizeandweldingparameters