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Enhancing heat and mass transfer to suppress void defects in friction stir welding by superimposing ultrasonic vibration.

Authors :
Wang, Xue
Zhang, Xiankun
Shi, Lei
Wu, Chuansong
Chen, Gaoqiang
Source :
Archives of Civil & Mechanical Engineering (Elsevier Science). Nov2023, Vol. 23 Issue 4, p1-16. 16p.
Publication Year :
2023

Abstract

Heat and mass transfer in the process of friction stir welding (FSW) determine the weld formation quality. Meanwhile, the formation of voids in FSW limits welding speed improvement and welding efficiency. Although superimposing ultrasonic vibration can be adopted as an effective means to restrain the formation of voids, the potential suppression mechanism was still unrevealed. Herein, a multi-physical model using the shear stress boundary conditions was put forward to quantitatively study the influence of ultrasonic vibration on the heat and mass transfer behaviors and the resulting weld formation which was also validated experimentally. Our results show that ultrasonic vibration in FSW slightly enhances the heat flux at the tool-workpiece interfacial contact surface as well as the plastic deformation heat generation near the tool. Therefore, the high-temperature area (higher than 690 K) near the tool pin side increases from 2.11 to 2.29 mm. The slightly higher heat rate and temperature enhance the fluidity of plastic material, resulting in an obvious increase in the flow velocity. As a consequence, the plastic material moves farther to fill the cavity at the rear advancing side, which is conducive to eliminating the void defects. The maximum strain rate on z = 2 mm horizontal plane at the AS is 206.7 s−1 in UVeFSW, while it is 13.5 s−1 in CFSW. The strain rate of the contact interface on AS increases by nearly 5 times, which implies an enhanced plastic material flow and is the main reason for suppressing void defects by superimposing ultrasonic vibration in FSW. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
16449665
Volume :
23
Issue :
4
Database :
Academic Search Index
Journal :
Archives of Civil & Mechanical Engineering (Elsevier Science)
Publication Type :
Academic Journal
Accession number :
173329954
Full Text :
https://doi.org/10.1007/s43452-023-00799-0