Friction Stir Spot Welding of Different Thickness Sheets of Aluminum Alloy AA6082-T6

Abstract

Friction stir spot welding (FSSW) is one of the important variants of the friction stir welding (FSW) process. FSSW has been developed mainly for automotive applications where the different thickness sheets spot welding is essential. In the present work, different thin thickness sheets (1 mm and 2 mm) of AA6082-T6 were welded using FSSW at a constant dwell time of 3 s and different rotation speeds of 400, 600, 800, and 1000 rpm. The FSSW heat input was calculated, and the temperature cycle experience during the FSSW process was recorded. Both starting materials and produced FSSW joints were investigated by macro- and microstructural investigation, a hardness test, and a tensile shear test, and the fractured surfaces were examined using a scanning electron microscope (SEM). The macro examination showed that defect-free spot joints were produced at a wide range of rotation speeds (400–1000 rpm). The microstructural results in terms of grain refining of the stir zone (SZ) of the joints show good support for the mechanical properties of FSSW joints. It was found that the best welding condition was 600 rpm for achieving different thin sheet thicknesses spot joints with the SZ hardness of 95 ± 2 HV0.5 and a tensile shear load of 4300 ± 30 N.

Special Issue: Advance in Friction Stir Processed Materials

“…In papers [ 17 , 18 ], the authors focused on selection of the parameters in friction stir spot-welding (FSSW) processes. Ataya et al [ 17 ] joined a low-carbon steel sheet (A283M-Grade C) with a brass sheet (CuZn40) by means of FSSW using different rotational speeds and dwell times to explore the effective range of parameters, enabling joints to be obtained with a high load-carrying capacity.…”

“…The authors also revealed that when the number of revolutions per spot ranged from 250 to 500, it was possible to produce joints with a high load-carrying capacity from 4 kN to 7.5 kN. In turn, in work [ 18 ], FSSW was used to join AA6082-T6 aluminium alloy sheets. Sheets with thicknesses of 1 mm and 2 mm were welded using different rotation speeds, while the dwell time was constant in all the variants.…”

Parametric Optimisation of Friction-Stir-Spot-Welded Al 6061-T6 Incorporated with Silicon Carbide Using a Hybrid WASPAS–Taguchi Technique

“…Hence, calculation of σ 2 is needed to determine the dispersal of outcomes in the distribution. Variance for the WSM and WPM can be calculated using Equations ( 4) and (5), respectively, and is shown in Table 5 [31][32][33]. For WSM:…”

“…During stirring, the temperature of the workpiece material rises due to friction, and reaches a value where the workpiece becomes soft and plastically deformed. When this process is ideally employed, the mixing of the workpiece material takes place without any significant change in its phase and microstructure, proving that the process is a solid-state joining process [5]. This can be attributed to the fact that the melting of the material leads to coarsening of the grains as grain boundaries break down during melting, and when the material cools down, those grains combine to form bigger grains, affecting the material properties.…”

Investigation of the Effects of Process Parameters for Friction Stir Spot Welding of Thin Al 6061 Sheet

“…Most studies on this issue in the literature have used aluminum sheets with a thickness of 2 mm or greater [3]. There have been few studies on the welding of thinner plates through using FSSW method [4]. For this reason, the welding of thin aluminum alloy sheets with a thickness of less than 2 mm using the FSSW method were investigated in this study.…”