Electrically Assisted Friction Stir Spot Welding of Aluminum Alloy to Advanced High Strength Steel

2017 ◽  
Author(s):  
Kai Chen ◽  
Xun Liu ◽  
Jun Ni
Keyword(s):  
Aluminum Alloy ◽  
Material Flow ◽  
Spot Welding ◽  
Aluminum Matrix ◽  
Welding Process ◽  
Friction Stir Spot Welding ◽  
Steel Matrix ◽  
Friction Stir ◽  
Lap Shear ◽  
Electrically Assisted

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.

Effects of Process Parameters on Friction Stir Spot Welding of Aluminum Alloy to Advanced High-Strength Steel

2017 ◽  
Vol 139 (8) ◽  
Author(s):  
Kai Chen ◽  
Xun Liu ◽  
Jun Ni
Keyword(s):  
Aluminum Alloy ◽  
Process Parameters ◽  
Cross Sections ◽  
Spot Welding ◽  
Dwell Time ◽  
Friction Stir Spot Welding ◽  
Thin Layers ◽  
Weld Strength ◽  
Friction Stir ◽  
Lap Shear

This paper studies a friction stir spot welding (FSSW) process that has been successfully applied to join aluminum alloy 6061-T6 to transformation-induced plasticity steel (TRIP) 780/800 steel. Cross sections of weld specimens show the formation of a hook with a swirling structure. A higher magnified scanning electron microscope (SEM) view of the swirling structure with energy dispersive X-ray spectroscopy (EDS) analysis reveals that it is composed of alternating thin layers of steel and Al–Fe intermetallic compounds (IMCs). To check the effect of different process parameters on the weld strength, the effects of tool plunge speed and dwell time were studied through the design of experiments (DOE) and analysis of variance (ANOVA) method. It shows that dwell time is a more dominant parameter in affecting the weld strength than plunge speed. Furthermore, investigation of failure using a lap shear tests reveals that cross nugget failure is the only failure mode. It also shows that cracks are initiated in the swirling structure at the tensile side of the weld nugget. After failure, a cleavage feature can be observed on the fractured surface.

Dissimilar Friction Stir Spot Welding without Key Hole between AZ31B Magnesium Alloy and 5052 Aluminum Alloy

2013 ◽  
Vol 652-654 ◽  
pp. 2320-2325 ◽  
Author(s):  
Xi Jing Wang ◽  
Ting Kai Guo ◽  
Zhong Ke Zhang ◽  
Pei Chung Wang ◽  
Ji Peng Shi ◽  
...  
Keyword(s):  
Aluminum Alloy ◽  
Magnesium Alloy ◽  
Spot Welding ◽  
Welding Process ◽  
Friction Stir Spot Welding ◽  
Tensile Fracture ◽  
Az31b Magnesium Alloy ◽  
Friction Stir ◽  
Welding Joint ◽  
The Impact

To study the impact of the welding process parameters on the spot weld surface molding, mechanical performance and the stir zone microstructure, we use friction stir spot welding without keyhole method which designed and developed by ourselves to carry on the lap welding between 1mm sheet of AZ31B magnesium alloy and 3mm sheet of 5052 aluminum alloy with magnesium on top and aluminum bottom. The result of the orthogonal test shows that the shoulder friction time have a greater impact on the forming of the surface of the welding joint; When the rotating speed of 1000 r/min, shoulder friction time of 4s, pin length of 3.5mm, the tensile shearing force of the welded joint achieves its maximum value of 2.46 KN.Through observating the microstructure of the welding joint’s section stirring zone, we found the typical joint microstructure of Dissimilar metal. Through analyzing the microstructure of the tensile fracture, we found that fracture was cleavage fracture.We also found the fracture mechanism of the welding joint was cleavage fracture in microcosm but brittle fracture macrocosm.

Visualization of Material Flow in a Refill Friction Stir Spot Welding Process Using Marker Materials

2010 ◽  
Vol 3 (1) ◽  
pp. 628-651 ◽  
Author(s):  
Sindhura Kalagara ◽  
Karim Heinz Muci-Kuchler ◽  
William Arbegast
Keyword(s):  
Material Flow ◽  
Spot Welding ◽  
Welding Process ◽  
Friction Stir Spot Welding ◽  
Friction Stir

Friction Stir Spot Welding Phenomena in Al Alloy 6061

2010 ◽  
Vol 638-642 ◽  
pp. 1243-1248
Author(s):  
Yutaka S. Sato ◽  
Mitsuo Fujimoto ◽  
Natsumi Abe ◽  
Hiroyuki Kokawa
Keyword(s):  
Material Flow ◽  
Spot Welding ◽  
Welding Process ◽  
Friction Stir Spot Welding ◽  
Al Alloy ◽  
Spiral Flow ◽  
Friction Stir ◽  
Fundamental Knowledge ◽  
Tool Rotation ◽  
Alloy 6061

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.

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