Visualization of Material Flow in the Refill Friction Stir Spot Welding Process

Author(s):  
S. K. Itapu ◽  
K. H. Muci-Küchler
Author(s):  
Kai Chen ◽  
Xun Liu ◽  
Jun Ni

This paper studies an electrically assisted friction stir spot welding (FSSW) process for joining aluminum alloy 6061-T6 to TRIP 780 steel. The electrical current shows to reduce the axial plunge force and assist the material flow of the aluminum matrix during the welding process. When electrical pulses and direct current (DC) with the same energy input are applied, the results show insignificant differences. Bulk material flow can be observed in the weld cross sections. A more uniform hook is generated at the Fe/Al interface after applying the current. Besides, the diffusion of aluminum atoms into the steel matrix is enhanced. Regarding the weld quality, electrically assisted FSSW improves the joint lap shear strength when compared with regular FSSW process.


2010 ◽  
Vol 638-642 ◽  
pp. 1243-1248
Author(s):  
Yutaka S. Sato ◽  
Mitsuo Fujimoto ◽  
Natsumi Abe ◽  
Hiroyuki Kokawa

Friction stir spot welding (FSSW), developed based on principle of friction stir welding, has been paid attention as a new solid-state spot welding process. Since FSSW can produce high-quality weld in Al alloys more easily than resistance spot welding, this process has been already used for construction of Al components in the automotive industries. Despite the large industrial interests in FSSW, fundamental knowledge on welding phenomena of this process has not been fully understood. In this study, FSSW phenomena, such as the consolidation mechanism, the microstructural evolution and the material flow, were examined in Al alloy 6061. This study clarified that the elliptical zone found in the vicinity of the pin hole on the cross section was characterized by the initially lapped surface of two sheets. Moreover, the following material flow was proposed; capture of the upper material with the threads on the pin surface, spiral flow along the tool rotation, and then release at the tip of the pin.


Author(s):  
Chaitanya Sharma ◽  
Ajay Tripathi ◽  
Vikas Upadhyay ◽  
Vijay Verma ◽  
Sumit K. Sharma

Author(s):  
Nasra Hannachi ◽  
Ali Khalfallah ◽  
Carlos Leitão ◽  
Dulce Rodrigues

Friction Stir Spot Welding involves complex physical phenomena, which are very difficult to probe experimentally. In this regard, the numerical simulation may play a key role to gain insight into this complex thermo-mechanical process. It is often used to mimic specific experimental conditions to forecast outputs that may be substantial to analyse and elucidate the mechanisms behind the Friction Stir Spot Welding process. This welding technique uses frictional heat generated by a rotating tool to join materials. The heat generation mechanisms are governed by a combination of sliding and sticking contact conditions. In the numerical simulation, these contact conditions are thoroughly dependent on the used friction model. Hence, a successful prediction of the process relies on the appropriate selection of the contact model and parameters. This work aims to identify the pros and cons of different friction models in modelling combined sliding-sticking conditions. A three-dimensional coupled thermo-mechanical FE model, based on a Coupled Eulerian-Lagrangian formulation, was developed. Different friction models are adopted to simulate the Friction Stir Spot Welding of the AA6082-T6 aluminium alloy. For these friction models, the temperature evolution, the heat generation, and the plastic deformation were analysed and compared with experimental results. It was realized that numerical analysis of Friction Stir Spot Welding can be effective and reliable as long as the interfacial friction characteristics are properly modelled. This approach may be used to guide the contact modelling strategy for the simulation of the Friction Stir Spot Welding process and its derivatives.


2019 ◽  
Vol 26 (10) ◽  
pp. 1562-1573 ◽  
Author(s):  
Behrouz Bagheri ◽  
Mahmoud Abbasi ◽  
Amin Abdollahzadeh ◽  
Hamid Omidvar

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