Effects of Cooling Conditions on Microstructure and Mechanical Properties of Friction Stir Welded Butt Joints of Different Aluminum Alloys

Bocchi, Sara; D’Urso, Gianluca Danilo; Giardini, Claudio; Maccarini, Giancarlo

doi:10.3390/app9235069

Cited by 16 publications

(11 citation statements)

References 31 publications

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“…Considering these combinations, it is possible to observe that cooling with water is the preferred solution; the only exception is for the AA2024. This piece of evidence agrees with what emerged from previous studies on the effects of the cooling solution on the microstructure of FSW joints 9,50 where it has been shown that the AA2024 is the least affected material by the water cooling. Subsequently, the welds were realized to verify the developed approach reliability defining a benchmark between the forecasted outputs and the experimental UTS and hardness in different areas of the joint.…”

Section: Fsw Process Optimization Through Psosupporting

confidence: 92%

Multiresponse optimization of friction stir welding by an integrated ANN-PSO approach

Quarto

Bocchi

D’Urso

et al. 2022

Proceedings of the Institution of Mechanical Engineers, Part B:

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The optimization of the process performance by considering each process parameter independently is the simplest approach, but its industrial applications are restricted owing to its very limited validity. To overcome this problem, many techniques such as multi-objective optimization techniques, Artificial Neural Network (ANN), and regression analysis have recently received great attention. In this paper, a multiresponse methodology for predicting the main properties and suggesting the optimal process parameters for Friction Stir Welded joints is presented. The dataset applied in the analysis was collected through experimental FSW tests performed on a CNC machine considering different aluminum alloys, process parameters, and cooling fluids. The integrated methodology involves an Artificial Neural Network and a heuristic algorithm, the Particle Swarm Optimization (PSO) and allows to set both input and output values leaving to the PSO algorithm the identification of the other values able to minimize or maximize a predefined objective function, in this case the maximization of both the UTS and the hardness values of the joints. This means that the ANN is interrogated iteratively until the optimum is reached. For this reason, the proposed methodology can be defined as a double direction method. In particular, the double-direction method refers to the possibility of identifying the optimal values of the process parameters (inputs) starting from the desired specifications (outputs) considering that, in the production reality, processes can be constrained by several factors. The results show a good reliability of the approach, since it has been demonstrated that it is able to generate prevision with an error of less than 5%.

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Section: Fsw Process Optimization Through Psosupporting

confidence: 92%

Multiresponse optimization of friction stir welding by an integrated ANN-PSO approach

Quarto

Bocchi

D’Urso

et al. 2022

Proceedings of the Institution of Mechanical Engineers, Part B:

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“…For the FWSed specimens, only the ultimate tensile strength (UTS) is reported, because it was not possible to evaluate the yield strength (YS) owing to the localization of the plastic straining of the specimens in the TMAZ/HAZ zone. The decrease in the mechanical properties at the thermomechanical and heat affected zones is the result of the modification in the microstructure of the alloy, with solubilization and reprecipitation of the straightening second phases, as reported in previous works by authors [10,14,18,22,24]. A good reproducibility was observed in the tensile strength of the FSWed joints, thus confirming the absence of macroscopic defects alongside the weld.…”

Section: Preparation Of the Weldssupporting

confidence: 83%

“…The zones close to the nugget, which has the microstructure altered both by the action of the mechanical straining and the thermal effect, is called thermo-mechanically affected zone (TMAZ); after this zone, moving away from the nugget toward the base metal, there is an area that has not 2 of 16 undergone mechanical straining, but only heating and therefore it is called heat-affected zone (HAZ). The microstructure and extension of these zone, nugget, TMAZ, and HAZ, depend on the size and shape of the pin, the thickness of the sheet, and the welding parameters, in particular the force exerted on the pin, its rotation speed, and feed rate [9,10]. Depending on the tool rotation side, "advancing side" and "retreating side" are defined [11].…”

Section: Introductionmentioning

confidence: 99%

Stress Corrosion Cracking of Friction Stir-Welded AA-2024 T3 Alloy

et al. 2020

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The paper is devoted to the study of stress corrosion cracking phenomena in friction stir welding AA-2024 T3 joints. Constant load (CL) cell and slow strain rate (SSR) tests were carried out in aerated NaCl 35 g/L solution. During the tests, open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS) were measured in the different zones of the welding. The results evidenced initial practical nobilty of the nugget lower compared to both heat-affected zone and the base metal. This effect can be mainly ascribed to the aluminum matrix depletion in copper, which precipitates in form of copper-rich second phases. In this zones, no stress corrosion cracking was noticed, but well-evident stress-enhanced intergranular corrosion occurred. This is due to the uneven distribution of platic deformation during the slow strain rate tests. Higher strain values are localized at the heat affected zone, where softening occurs. On the contrary, stress values at the nugget are not sufficient to favor both the initiation and propagation of stress corrosion cracks. In the range of processing parameter studied in this experimental work, the stress corrosion cracking susceptibility of the friction stir welding (FSW)-ed alloy is then similar to that of the base metal.

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“…Peak temperature, incubation time, and stir action are the vital parameters that determine the evolution of IMCs. 53 When FSW is carried out in the actively cooled and vibrated environments, IMCs in the stir zone are no longer a concern, as their evolution is highly restricted due to the lower peak temperature and higher stir action. The vibration breaks the IMC layer into small parts with uniform distribution in the weld zone.…”

Section: Mechanical Properties and Fracture Surface Analysismentioning

confidence: 99%

A modified version of friction stir welding process of aluminum alloys: Analyzing the thermal treatment and wear behavior

Abdollah-zadeh

Bagheri

Abbasi

et al. 2021

Proceedings of the Institution of Mechanical Engineers, Part L:

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In this article, the effect of vibration and cooling media on the friction stir welding of 5083Al alloy is investigated. The vibration was introduced by the motor into the fixture inserted under the workpiece while a cooling media (water and lubrication oil) flowed into a canal in the fixture beneath the weld path. A constant rotation speed of 1250 r/min and a traveling speed of 90 mm/min were used for all the welding conditions. The thermal analysis measured by several thermocouples indicated that friction stir vibration welding (FSVW) provided maximum temperature distribution in the workpiece, while friction stir welding with the water cooling exhibited the lowest temperature value. The microstructure observations were conducted by optical microscope, scanning electron microscopy, and transmission electron microscopy. The results indicated substantial grain refinement when vibration and water cooling were simultaneously applied during the friction stir welding process. The hardness values increased from 50 to around 78 (Hv) for friction stir welding and FSVW with water systems, respectively. The joint efficiency (the ratio of the joint strength to the base metal strength) of the joint fabricated by FSVW with water cooling was around 87%, while this quantity was about 66% for the friction stir welding joint. Fracture analysis indicated more ductile behaviors for the samples fabricated by FSVW with the coolant systems. Furthermore, the joint fabricated by FSVW with water cooling exhibited the best wear resistance among all the samples in a pin-on-disk wear test.

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Effects of Cooling Conditions on Microstructure and Mechanical Properties of Friction Stir Welded Butt Joints of Different Aluminum Alloys

Cited by 16 publications

References 31 publications

Multiresponse optimization of friction stir welding by an integrated ANN-PSO approach

Multiresponse optimization of friction stir welding by an integrated ANN-PSO approach

Stress Corrosion Cracking of Friction Stir-Welded AA-2024 T3 Alloy

A modified version of friction stir welding process of aluminum alloys: Analyzing the thermal treatment and wear behavior

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