Experimental quality and strength evaluation of friction stir spot welding of aluminum sheets using flat tool with miniature profile

Friction Stir welding (FSW) is a solid state joining process developed by TWI (The Welding Institute) in 1991. This technology is suitable for joining different materials even considered difficult to be welded using more traditional techniques and it is appropriate to weld materials in different configurations (such as butt, lap, circumferential, T-joint etc). Recently, starting from the FSW approach, a new technology called Friction Stir Spot Welding (FSSW) was developed. In this case, instead of moving along the weld seam, the tool only indents two overlapped parts. In some applications, this technology can be considered as a valid alternative for single point joining processes like resistance spot welding (RSW) and riveting processes. This work deals with an experimental study of the FSSW process for the lap-joining of thin aluminum sheets. In particular, an experimental campaign was performed on AA6060 T6 aluminum sheets having a thickness equal to 2 mm. The FSSW process was applied on couples of overlapped sheets by varying the tool rotational speed, and by keeping fixed the other process parameters, such as axial feed rate, indentation depth, and dwell time. Welding forces distributions were recorded during the process. Preliminary tensile tests and metallurgical analyses were also performed to evaluate the quality of the joints as function of the chosen process parameters. A numerical model of the FSSW process was developed and implemented using the commercial FEM code Deform 3D. The model parameters were set according to the experimental evidence.

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Effect of Rotational Speed and Flat Tool Diameter on the Zn Distribution of the Dissimilar Metals Friction Stir Spot Welded between Aluminum Alloy 5083 H321 and Galvanized Steel

MATEC Web of Conferences ◽

10.1051/matecconf/201926902004 ◽

2019 ◽

Vol 269 ◽

pp. 02004

Author(s):

Bintang Adhi Guna ◽

Nurul Muhayat ◽

Triyono

Keyword(s):

Rotational Speed ◽

Spot Welding ◽

Friction Stir Spot Welding ◽

Galvanized Steel ◽

Dissimilar Metals ◽

Zn Diffusion ◽

Friction Stir ◽

Zn Distribution ◽

Tool Diameter ◽

Flat Tool

Friction stir spot welding (FSSW) was developed to join the dissimilar materials as an alternative for replacing the resistance spot welding (RSW). In the case of dissimilar metals welded between aluminum and galvanized steel, Zn can decompose and diffuse in both steel and aluminum so it can increase the joint strength. Due to this reason, it is important to explore the Zn distribution based on the parameter of the friction stir spot welding. The lap joint configuration was used in this work where aluminum plate was placed on the top of steel. Aluminum thickness was 3 mm, while steel thickness was 1 mm. The constant depth of plunge, dwell time, and penetration rate were 2.7 mm, 3 seconds, and 0.9 mm/sec respectively. Flat tool with diameters of 10 mm, 12 mm and 14 mm were used for FSSW processes and for each flat tool diameter, four levels of the rotational speed of 1000 rpm, 1200 rpm, 1600 rpm and 2000 rpm were performed. The Zn distribution was evaluated using the SEM and EDS analysis. Due to the heat generation during FSSW process, materials around the tools will soften and then flow to follow the centrifugal force. The rotational speed and the flat tool diameter affected the distance and the shape of Zn diffusion flow. The distance of Zn diffusion both horizontal and vertical direction increased as increasing the rotational speed and the flat tool diameter.

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Flat friction stir spot welding of three 6061-T6 aluminum sheets

Journal of Materials Processing Technology ◽

10.1016/j.jmatprotec.2018.09.031 ◽

2019 ◽

Vol 264 ◽

pp. 414-421 ◽

Cited By ~ 11

Author(s):

Yufeng Sun ◽

Hidetoshi Fujii ◽

Shijie Zhu ◽

Shaokang Guan

Keyword(s):

Spot Welding ◽

Friction Stir Spot Welding ◽

Friction Stir ◽

Aluminum Sheets

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Taguchi analysis of dissimilar aluminum sheets joined by friction stir spot welding

Pamukkale University Journal of Engineering Sciences ◽

10.5505/pajes.2016.06641 ◽

2016 ◽

Vol 22 (1) ◽

pp. 17-23

Author(s):

Mustafa Kemal Bilici ◽

Barkın Bakır ◽

Yahya Bozkurt ◽

İrfan Çalış

Keyword(s):

Spot Welding ◽

Friction Stir Spot Welding ◽

Taguchi Analysis ◽

Friction Stir ◽

Aluminum Sheets

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Microstructure and Mechanical Performances Analyses on Probeless Friction Stir Spot Welds of AA6061-T6 Aluminum Sheets

10.21203/rs.3.rs-1014036/v1 ◽

2021 ◽

Author(s):

Yu Guishen ◽

Chen Xin ◽

Wu Zitao ◽

Zhang Guanchen ◽

Chen Yixiong

Keyword(s):

Mechanical Properties ◽

Spot Welding ◽

Shear Failure ◽

Friction Stir Spot Welding ◽

Welding Parameter ◽

Mixed Mode Fracture ◽

Tensile Shear ◽

Friction Stir ◽

Aluminum Sheets ◽

Mechanical Performances

Abstract Probeless friction stir spot welding (PFSSW) is a variation of conventional friction stir spot welding (CFSSW), which solves the keyhole defect in CFSSW welds. In this work, four types of probeless tools were designed based on helix and spiral feature: small curvature helix (involute tool, IT), large curvature helix (archimedes tool, AT), spiral line (scroll tool, ST) and no feature (flat tool, FT). AA6061-T6 sheets with a thickness of 1.5 mm were welded using the designed probeless welding tools. The effect of tool shapes on the microstructure and mechanical properties of friction stir spot welded AA 6061-T6 aluminum alloy sheets was investigated using different rotational speeds, plunging depths and dwell times. The Taguchi method was utilized to obtain the optimal welding parameter combination for the four tools. And, the tensile-shear mechanical properties of FSSW specimens were characterized under the optimal parameters. The results show that a basin-shaped profile appeared in the weld metallography using the groove tools. The tensile shear failure load (TSFL) of IT (~6.97 kN) was higher than that of ST (~6.49 kN), AT (~6.19 kN) and FT (~5.67 kN), sequentially. Three different fracture modes, interfacial fracture, plug fracture and mixed-mode fracture were observed in the tensile-shear tests of weld specimens.

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