Evaluation of the formation of intermetallic compounds at the intermixing lines and in the nugget of dissimilar steel/aluminum friction stir welds

Elnabi, Mohamed Mohamed Abd; Osman, T. A.; Mokadem, A. El; Elshalakany, Abou Bakr

doi:10.1016/j.jmrt.2020.07.027

Cited by 38 publications

(26 citation statements)

References 22 publications

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“…The IMC thickness formed during the friction stir butt welding of aluminum alloy to steel ranges between 0.25 and 5 µm [40][41][42]. This IMC thickness compared to that obtained in other studies [36] for aluminum steel FSW can be considered low. This is attributed to the low tool rotation rates used in this study which significantly reduced the heat input experienced during the welding process.…”

Section: Microstructure Analysismentioning

confidence: 61%

“…Due to the offset towards the aluminum side, it can be seen that both materials experienced sufficient stirring in the weld zone, where tiny steel fragments from the advanced side (AS) move to the retreating side (RS) and mixed with the Al, while the aluminum moves from the front of the tool to the back of the tool to generate the joint in the solid state. Recently, Abd Elnabi et al [36] conducted an experimental investigation to study the dissimilar FSW of pure aluminum AA1050 and annealed low carbon steel. They reported in their optimization step that all joints made at rotational speeds from 255 to 1225 rpm, traverse speed from 422 to 25 mm/min, and pin offset from 0 to 3 mm have sever surface defects.…”

Section: Mechanical Testing and Failure Investigationsmentioning

confidence: 99%

“…Based on the aforementioned research works conducted on Al/steel dissimilar welding by FSW, it can be said that there are is a number of FSW parameters affecting the quality and properties of the joints, such as the tool rotation rate, welding speed, tool offset towards the aluminum side, tool tilt angle and shoulder plunge depth (downward force) [32][33][34][35][36]. In addition, a knowledge gap exists about the elimination of the IMC phase formations due to their detrimental effects on the tensile properties and the quality of the joints.…”

Section: Introductionmentioning

confidence: 99%

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Dissimilar Friction Stir Welding of AA2024 and AISI 1018: Microstructure and Mechanical Properties

Ahmed

Jouini

Alzahrani

et al. 2021

Metals

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This study investigated the effect of the friction stir welding rotation rate and welding speed on the quality and properties of the dissimilar joints between aluminum and carbon steel. Plates of 4 mm thickness from both AA2024 and AISI 1018 were successfully friction stir butt welded at rotation speeds of 200, 250, and 300 rpm and welding speeds of 25, 50, and 75 mm/min. The joint quality was investigated along the top surface and the transverse cross-sections. Further investigation using scanning electron microscopy was conducted to assess the intermetallic layers and the grain refining in the stir zone. The mechanical properties were investigated using tensile testing for two samples for each weld that wire cut perpendicular to the welding direction and the hardness profiles were obtained along the transverse cross-section. Both the top surface and the transverse cross-section macrographs indicated defect free joints at a rotation rate of 250 rpm with the different welding speeds. The intermetallic compounds (IMCs) formation was significantly affected by the heat input, where there is no formation of IMCs at the Al/steel interfaces when higher traverse speed (75 mm/min) or lower rotation speed (200 rpm) were used, which gave the maximum tensile strength of about 230 MPa at the low rotation speed (200 rpm) along with 3.2% elongation. This is attributed to the low amount of heat input (22.32 J/mm) experienced. At the low traverse speed (25 mm/min and 250 rpm), a continuous layer of Al-rich IMCs FeAl3 is formed at the joint interface due to the high heat input experienced (79.5 J/mm). The formation of the IMCs facilitates fracture and reduced the tensile strength of the joint to about 98 MPa. The fracture mechanism was found to be of mixed mode and characterized by a cleavage pattern and dimples. The hardness profiles indicated a reduction in the hardness at the aluminum side and an increase at the steel side.

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Section: Microstructure Analysismentioning

confidence: 61%

Section: Mechanical Testing and Failure Investigationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Dissimilar Friction Stir Welding of AA2024 and AISI 1018: Microstructure and Mechanical Properties

Ahmed

Jouini

Alzahrani

et al. 2021

Metals

View full text Add to dashboard Cite

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“…Figure 3 shows the macrograph and schematic view of flow pattern in the welded joints in various cooling conditions. The conventional FSWed joint shows a smooth curvy interface between base metals and some stretch of steel in the aluminum side at the bottom of joint [ 34 ].…”

Section: Resultsmentioning

confidence: 99%

“…These studies and examinations have indicated that the cooling rate and peak temperature have significant effects on the joint mechanical features. For instance, the joint mechanical features will mostly depend on the final grain size, which is affected by heat input, whenever the welding peak temperature becomes lower than the phase transformation temperature [ 33 ]; while in different circumstances, when the welding peak temperature is higher than the phase transformation, the parameter which will play a significant role in the last phase composition and morphology is the cooling rate [ 34 ]. Furthermore, the grain structure before the phase transformation is very crucial [ 35 ].…”

Section: Introductionmentioning

confidence: 99%

Effects of Rapid Cooling on Properties of Aluminum-Steel Friction Stir Welded Joint

et al. 2021

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In this study, dissimilar sheets including AA3003 aluminum and A441 AISI steel were welded via cooling-assisted friction stir welding (FSW). Three different cooling mediums including forced CO2, forced water, and forced air were employed, and a non-cooled sample was processed to compare the cooling-assisted condition with the traditional FSW condition. The highest cooling rate belongs to CO2 and the lowest cooling rate belongs to the non-cooled sample as FSW. The best macrograph without any segregation at interface belongs to the water-cooled sample and the poorest joint with notable segregation belongs to the CO2 cooling FSW sample. The CO2 cooling FSW sample exhibits the smallest grain size due to the suppression of grain growth during dynamic recrystallization (DRX). The intermetallic compound (IMC) thickening was suppressed by a higher cooling rate in CO2 cooling sample and just Al-rich phase was formed in this joint. The lowest cooling rate in the FSW sample exhibits formation of the Fe rich phase. The IMC layers were thicker at the top of the weld due to closeness with the heat generation source. The water cooling sample exhibits the highest tensile strength due to proper mechanical bonding simultaneously with optimum IMC thickness to provide appropriate metallurgical bonding. Fractography observation indicates that there is a semi-ductile fracture in the water cooling sample and CO2 cooling sample exhibits more brittle fracture. Hardness evaluation reveals that the higher the cooling rate formed, the higher the hardness in stir zone, and hardness changes in the aluminum side were higher than the steel side.

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Optimization of process parameters for friction stir welding of dissimilar aluminum alloys using different Taguchi arrays

Elnabi

Mokadem

Osman

2022

Int J Adv Manuf Technol

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A statistical optimization based on experimental work was conducted to consider ultimate tensile strength (UTS) and elongation of dissimilar joints between AA5454 and AA7075 by friction stir weld (FSW). The goal of this work is to develop a comparative study of the optimization of FSW parameters using different orthogonal arrays, i.e., L12 and L16. Four parameters correlated to softening and forging requirements (rotational speed, traverse speed, tilt angle, and plunge depth), one parameter associated with the location of base metal in the dissimilar joint, and two parameters related to an FSW tool (pin profile and Dshoulder/dpin ratio) were considered and arranged in the employed arrays. Moreover, the investigation explored the microstructure and fractography of dissimilar joints and base metals by using optical and scanning electron microscopes. The results showed that the L16OA is more accurate than L12OA for the optimization of seven parameters due to the small statistical errors. For UTS, the errors range from 0.78 to 24% for L16OA and from 27.23 to 44.14% for L12OA. For elongation, the errors run from 11 to 12.9% for L16OA and from 33.77 to 49.73% for L12OA. The accuracies of generated models range from 50 to 99.5% for L16OA and range from 30.7 to 94.9% for L12OA. Tightening the levels (narrow domain) is the main reason for switching some optimum levels between both arrays. The highest UTS obtained is 221 MPa based on the optimum levels attained from L16OA, and the highest elongation is 12.83% according to the optimum levels acquired from L12OA. Despite the deficiency of effective intermixing, the study revealed that FSW acceptably could assemble joints between AA5454 and AA7075, presenting the proficiency of FSW with welding dissimilar aluminum alloys.

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Evaluation of the formation of intermetallic compounds at the intermixing lines and in the nugget of dissimilar steel/aluminum friction stir welds

Cited by 38 publications

References 22 publications

Dissimilar Friction Stir Welding of AA2024 and AISI 1018: Microstructure and Mechanical Properties

Dissimilar Friction Stir Welding of AA2024 and AISI 1018: Microstructure and Mechanical Properties

Effects of Rapid Cooling on Properties of Aluminum-Steel Friction Stir Welded Joint

Optimization of process parameters for friction stir welding of dissimilar aluminum alloys using different Taguchi arrays

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