Surface and mechanical characterization of stationary shoulder friction stir welded lap joints: experimental and numerical approach

Buffa, Gianluca; Fratini, Livan; Impero, Filomena; Masnata, A.; Scherillo, Fabio; Squillace, Antonino

doi:10.1007/s12289-020-01574-9

Cited by 15 publications

(7 citation statements)

References 25 publications

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“…With increasing distance from the shoulder, the strain rate in both materials decreased. This trend shows that at lower areas of the stir zone, stirring action decreases [72][73][74].…”

Section: Strain Rate and Materials Velocitymentioning

confidence: 76%

Effect of Pin Shape on Thermal History of Aluminum-Steel Friction Stir Welded Joint: Computational Fluid Dynamic Modeling and Validation

et al. 2021

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This article studied the effects of pin angle on heat generation and temperature distribution during friction stir welding (FSW) of AA1100 aluminum alloy and St-14 low carbon steel. A validated computational fluid dynamics (CFD) model was implemented to simulate the FSW process. Scanning electron microscopy (SEM) was employed in order to investigate internal materials’ flow. Simulation results revealed that the mechanical work on the joint line increased with the pin angle and larger stir zone forms. The simulation results show that in the angled pin tool, more than 26% of the total heat is produced by the pin. Meanwhile, in other cases, the total heat produced by the pin was near 15% of the total generated heat. The thermo-mechanical cycle in the steel zone increased, and consequently, mechanical interlock between base metals increased. The simulation output demonstrated that the frictional heat generation with a tool without a pin angle is higher than an angled pin. The calculation result also shows that the maximum heat was generated on the steel side.

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“…With increasing distance from the shoulder, the strain rate in both materials decreased. This trend shows that at lower areas of the stir zone, stirring action decreases [72][73][74].…”

Section: Strain Rate and Materials Velocitymentioning

confidence: 76%

Effect of Pin Shape on Thermal History of Aluminum-Steel Friction Stir Welded Joint: Computational Fluid Dynamic Modeling and Validation

et al. 2021

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“…The longitudinal section view of the strain rate simulation results is shown in Figure 7 a. Due to obtained results, with increasing TPD (heat input in SZ), the strain rate increased [ 60 ]. With increasing contact area between the FSW tool’s pin and flange at higher TPD, the flange side has a higher strain rate [ 61 , 62 , 63 ].…”

Section: Resultsmentioning

confidence: 99%

Effects of FSW Tool Plunge Depth on Properties of an Al-Mg-Si Alloy T-Joint: Thermomechanical Modeling and Experimental Evaluation

et al. 2021

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One of the main challenging issues in friction stir welding (FSW) of stiffened structures is maximizing skin and flange mixing. Among the various parameters in FSW that can affect the quality of mixing between skin and flange is tool plunge depth (TPD). In this research, the effects of TPD during FSW of an Al-Mg-Si alloy T-joint are investigated. The computational fluid dynamics (CFD) method can help understand TPD effects on FSW of the T-joint structure. For this reason, the CFD method is employed in the simulation of heat generation, heat distribution, material flow, and defect formation during welding processes at various TPD. CFD is a powerful method that can simulate phenomena during the mixing of flange and skin that are hard to assess experimentally. For the evaluation of FSW joints, macrostructure visualization is carried out. Simulation results showed that at higher TPD, more frictional heat is generated and causes the formation of a bigger stir zone. The temperature distribution is antisymmetric to the welding line, and the concentration of heat on the advancing side (AS) is more than the retreating side (RS). Simulation results from viscosity changes and material velocity study on the stir zone indicated that the possibility of the formation of a tunnel defect on the skin–flange interface at the RS is very high. Material flow and defect formation are very sensitive to TPD. Low TPD creates internal defects with incomplete mixing of skin and flange, and high TPD forms surface flash. Higher TPD increases frictional heat and axial force that diminish the mixing of skin and flange in this joint. The optimum TPD was selected due to the best materials flow and final mechanical properties of joints.

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“…A temperature measuring tool [9] was used to process the thermocouple signals. To compensate for the cooling effect of the stationary shoulder [6] and to ensure more similar welding conditions when applying different tools [10], closed-loop temperature control was applied as described by Bachmann et al [11]. The control algorithm was implemented in a real-time system (MicroLabBox, dSPACE GmbH, Paderborn, Germany).…”

Section: Methodsmentioning

confidence: 99%

“…Values taken from the literature are listed in Table 1. Aside from conventional tools, stationary shoulder tools can be used to further improve the surface of friction stir lap welds [6]. 2 Calculated by using Eq.…”

Section: Introductionmentioning

confidence: 99%

Efficient Build-Up of High-Strength Aluminum Structures Using Friction Stir Additive Manufacturing

Sigl

Danninger

Bernauer

et al. 2022

KEM

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Friction Stir Additive Manufacturing (FSAM) is a novel process with which large-scale aluminum structures can be produced from high-strength alloys such as the 7xxx series. Due to the prevalence of these alloys in airplanes and rockets, the process offers high application potential, for example in fabricating stringers and stiffeners. The building process in FSAM is characterized by sequentially stacking and friction stir lap welding (FSLW) metal sheets. Before adding the next layer, the surface is machined (i.e., by milling). So far, this is a necessary step to enable gap-free welding of the layers, which results in increased costs and reduced layer heights. The investigations described in this paper were aimed at improving the weld surface quality to enable defect-free FSAM without the additional machining step. For this, FSLW was conducted using different welding tools. The resulting welds were evaluated based on superficial and internal characteristics as well as the mechanical properties (shear strength). With a welding tool in which both a rotating and a stationary shoulder were combined, defect-free weld seams with a mean underfill and a mean flash height of 0.07 mm were produced. In a subsequent study, it was proven that defect-free FSAM without surface machining is possible up to the fifth layer using the combined welding tool.

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Surface and mechanical characterization of stationary shoulder friction stir welded lap joints: experimental and numerical approach

Cited by 15 publications

References 25 publications

Effect of Pin Shape on Thermal History of Aluminum-Steel Friction Stir Welded Joint: Computational Fluid Dynamic Modeling and Validation

Effect of Pin Shape on Thermal History of Aluminum-Steel Friction Stir Welded Joint: Computational Fluid Dynamic Modeling and Validation

Effects of FSW Tool Plunge Depth on Properties of an Al-Mg-Si Alloy T-Joint: Thermomechanical Modeling and Experimental Evaluation

Efficient Build-Up of High-Strength Aluminum Structures Using Friction Stir Additive Manufacturing

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