scholarly journals Refill Friction Stir Spot Welding of Dissimilar 6061/7075 Aluminum Alloy

2019 ◽  
Vol 38 (2019) ◽  
pp. 69-75 ◽  
Author(s):  
Zhenlei Liu ◽  
Kang Yang ◽  
Dejun Yan

AbstractRefill friction stir spot welding (RFSSW) was used to join 6061-T6 and 7075-T6 aluminum alloys in this work. Different sheet configurations and welding parameters were used to optimize joint strength. The effect of sleeve plunge depth on the microstructure and mechanical properties of the joints were investigated. The results showed that no defects were obtained when 6061-T6 aluminum alloy was placed as the upper sheet. The lap shear failure load of the joint using 6061-T6 aluminum alloy as the upper sheet was higher than that using 7075-T6 as the upper sheet. The maximum failure load of 12,892 N was attained when using the sleeve plunge depth of 3.6 mm. The joint failed at the upward flowing 7075 near the hook.

2020 ◽  
Vol 39 (1) ◽  
pp. 663-670
Author(s):  
Tao Wang ◽  
Xue Gong ◽  
Shude Ji ◽  
Gang Xue ◽  
Zan Lv

AbstractIn this work, thin aluminum alloy sheets with thickness of 0.8 mm were friction stir lap welded using small shoulder plunge depths of 0 and 0.1 mm. The joint formation, microstructure and mechanical properties were investigated. Results show that voids appear inside the stir zone when the small plunge depth of 0 mm is used because the tool shoulder cannot exert a good material-collecting effect at such low plunge depth. A plunge depth of 0.1 mm causes tight contact between the shoulder and the material and thus results in good material-collecting effect, which is helpful to eliminate the void. Sound joints are attained at a wide range of welding parameters when using the shoulder plunge depth of 0.1 mm. No crack is observed inside the bonding ligament. The joints own higher failure loads when the retreating side (RS) of the joint bares the main load during the lap shear tests. The shear failure load first increases and then decreases with increasing the rotating and welding speeds, and the maximum failure load of 6419 N is obtained at 600 rpm and 150 mm/min. The hardness of the joint presents a “W” morphology and the minimum hardness is obtained at the heat affected zone. The joints present tensile fracture and shear fracture when the advancing side and RS bare the main loads, respectively.


2020 ◽  
pp. 009524432096152
Author(s):  
Asil Ayaz ◽  
Aydin Ülker

In this study, a new method was proposed to reduce the keyhole volume with friction stir spot welding process and improve the lap joint shear load-carrying capacity of the weld by analyzing the effects of tool rotation speed, plunge depth and dwell time on the weld. Single lap shear tests were carried out to determine the influences of the welding parameters on the mechanical behavior of the welds. The quality of the joint was evaluated by examining the characteristics of the joint as a result of the lap joint shear load. For friction stir spot welding of the acrylonitrile butadiene styrene samples, the experiments were designed according to Taguchi’s L9 orthogonal array in a randomized way. From the analysis of variance and the signal-to-noise ratio, the significant parameters and the optimum combination level of the parameters were obtained. It was found that using a tool rotation of 1000 rpm, plunge depth 11.5 mm and dwell time of 40 s, an improved joint strength can be obtained. The results showed that joint strength was improved by an amount of 20% as compared with the optimum welding parameters to the initial welding parameters. Macrostructure examination plays an important role to determine the joint strength and evaluate the influences of each welding parameters. So, weld morphology was investigated by morphological analysis and visual comparisons. It was also observed failure modes for fractured samples having the highest, moderate and lowest lap joint shear load.


Author(s):  
Alexandre da Silva Alves ◽  
Levi Mello dos Santos ◽  
Pedro Brito ◽  
Sara Silva Ferreira de Dafé ◽  
Ana Paula de Oliveira Costa

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.


Author(s):  
Kai Chen ◽  
Xun Liu ◽  
Jun Ni

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.


2021 ◽  
Vol 2129 (1) ◽  
pp. 012002
Author(s):  
N N S M Shobri ◽  
S R Pedapati ◽  
M Awang

Abstract Simulation is limited and remains briefly addressed in the literature of friction stir spot welding (FSSW) process in joining dissimilar copper and aluminium. Thus, this study simulated the FSSW process of copper and aluminium to investigate the peak temperature during the plunging phase produced by all possible combinations of levels for tool rotational speed, plunge rate, and plunge depth according to the full factorial design. The modeling was established by Coupled Eulerian-Lagrangian (CEL) model and ‘dynamic, temperature-displacement, explicit’ analysis. The highest peak temperature of 994.4 oC was produced by 2400 rpm rotational speed, 100 mm/min plunge rate, and 1.6 mm plunge depth. The combination was suggested to be the optimum welding parameters in joining copper to aluminium as sufficient heat input was essential to soften the area around the welding tool and adequately plasticize the material. Three sets of confirmation tests presented consistent responses with a mean peak temperature of 994.4 °C, which validated that the response produced by the suggested optimum welding parameters was reliable. The statistical result reported that the variability in the factors could explain 84.12% of the variability in the response. However, only the rotational speed and plunge depth were statistically significant. The residual plots showed that the regression line model was valid.


2018 ◽  
Vol 99 (5-8) ◽  
pp. 1927-1936 ◽  
Author(s):  
Camila Caroline de Castro ◽  
Athos Henrique Plaine ◽  
Nelson Guedes de Alcântara ◽  
Jorge Fernandez dos Santos

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