A Comparative Investigation on Conventional and Stationary Shoulder Friction Stir Welding of Al-7075 Butt-Lap Structure

Chen, Yu; Li, Huaying; Wang, Xiaoyu; Ding, Hua; Zhang, Fenghe

doi:10.3390/met9121264

Cited by 15 publications

(7 citation statements)

References 33 publications

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“…From Figure 5 a–i, it can be seen that certain visible defects, such as hooks and kiss bonding, are present in various layers of the FSAM part which is identical to the findings reported by Yu Chen et al [ 39 ] and Wronska et al [ 40 ]. Since FSAM consist of multiple layers formed by repeated FSLW technique, the intricate nature of the material flow during this process leads to several types of flaws.…”

Section: Resultssupporting

confidence: 86%

Novel Technique for Design and Manufacture of Alternating Gradient Composite Structure of Aluminum Alloys Using Solid State Additive Manufacturing Technique

Venkit

Selvaraj

2022

Materials

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This work analyzes a novel solid-state manufacturing approach of a friction stir additive manufacturing (FSAM) technique for fabricating multiple layers of alternating gradient composite structure using alternate layers of AA6061-T6 and AA7075-T6 aluminum alloys of 3 mm thickness. The evolution of the microstructure along the build direction and its impact on the tensile and microhardness properties were examined using optical microscopy, tensile tests, and Vickers microhardness tests. Nonuniform microstructures were detected along the build direction, and it was concluded that the most productive part of the construction was the nugget zone, which had fine equiaxed grains. It was identified that the grain sizes and precipitate sizes were affected by the varying thermal cycles created by the multiple passes of the tool. These events were identified as the primary reasons for the increase in strength and hardness of the FSAM build from the lower layer to the upper layer. In the final FSAM build the maximum hardness value was obtained as 182.3 HV and the ultimate tensile strength (UTS) was 420 MPa both of which were identified at the topmost layer. Moreover, the postmortem of the fractured samples revealed that the cause of failure was a combination of both ductile and brittle fractures. The findings of this study suggest that the FSAM approach may be used to fabricate large structures that are free of defects having expected mechanical characteristics and hence the newly fabricated composite can be used as a suitable substitute for the conventional AA6061 material applied in automobile components for its improved performance.

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Section: Resultssupporting

confidence: 86%

Novel Technique for Design and Manufacture of Alternating Gradient Composite Structure of Aluminum Alloys Using Solid State Additive Manufacturing Technique

Venkit

Selvaraj

2022

Materials

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“…2021; 18(20): 4 6 of 10 mm in both sides, this is the area till which the grains are influenced by the heat produced throughout welding. The 'W' shape microhardness profile observed in Figure 7 is common for these aluminum alloys welded by FSW [38][39][40][41]. Figure 5 Hardness plot for welded cross section.…”

Section: Hardness Testingmentioning

confidence: 90%

Study of Material Flow and Mechanical Properties of Friction Stir Welded AA2024 with AA7075 Dissimilar Alloys using Top-Half-Threaded Pin Tool

2021

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This research work was aimed at evaluating the material flow behavior and mechanical properties of dissimilar aluminum alloys (2024 and 7075) joints prepared by friction stir welding using a tool with top-half-threaded pin. Macro and microstructural study for material flow investigation was carried out. Whereas mechanical properties of welded joints are examined using tensile and micro-Vicker's hardness tests. Zeiss EVO 18 SEM was used for the fractographic study. Average grain sizes were determined at various weld regions. The effect of grain size with the hardness and strength has been discussed. The results demonstrate that the thread's location on the pin significantly affects the flow of the material. The area where the material has been severely plasticized and moved was located at the weld root. Hence welding root defects like void, pinhole, insufficient filling, etc. are avoided. The tensile strength of friction stir welded joint was 312.7 MPa, equivalent to the joint efficiency of 66.5 %. HIGHLIGHTS The threaded pin tool pushed the soft material downwards hence avoiding root defects. The onion ring structure formation has been observed The tool pin is responsible for creating two separate regions at weld line: Low flow region at the top and high flow region at central areas The maximum tensile strength obtain is 312.7 MPa and 66.5 % joint efficiency GRAPHICAL ABSTRACT

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“…Compared with the simple butt- or lap-joint, fabricating the butt-lap joint becomes more difficult because of its asymmetrical structure. Currently, the butt-lap joint is widely used in the train industry [ 23 ], and the demand for the dissimilar Al/steel butt-lap joint is also increasing. Thus, it becomes necessary to elevate the quality of the Al/steel butt-lap joint.…”

Section: Introductionmentioning

confidence: 99%

Improving the Quality of Dissimilar Al/Steel Butt-Lap Joint via Ultrasonic-Assisted Friction Stir Welding

Zhang

2022

Materials

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A dissimilar AA7075/Q235 butt-lap joint was fabricated via ultrasonic-assisted friction stir welding (UaFSW), and the characteristics of the UaFSW joint were investigated systematically. The acoustoplastic effect of the ultrasonic vibration led to the softening of the materials and enhanced the material flow during welding, decreasing the volume of welding defects in the nugget zone of the UaFSW joint. With the help of ultrasonic vibration, a smooth and thin intermetallic compounds (IMCs) layer could generate along the Al/steel interface at the top of nugget zone, which possibly consisted of Al5Fe2 and Al13Fe4 phases. However, the positive effects of the ultrasonic vibration were weakened at low temperatures; consequently, the IMCs layer became discontinuous at the bottom of the nugget zone and the welding defects also formed. The ultrasonic vibration accelerated the dynamic recrystallization and refined the microstructures in the nugget zone due to the increased strain rate and stored energy. As a result, the UaFSW joint exhibited a better mechanical performance in comparison to the FSW joint, and the increment in the peak tensile load/elongation was more than twice. In addition, the UaFSW joint failed in the nugget zone along with the Al/steel interface, and the fracture mode was a mixture of ductile and brittle.

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A Comparative Investigation on Conventional and Stationary Shoulder Friction Stir Welding of Al-7075 Butt-Lap Structure

Cited by 15 publications

References 33 publications

Novel Technique for Design and Manufacture of Alternating Gradient Composite Structure of Aluminum Alloys Using Solid State Additive Manufacturing Technique

Novel Technique for Design and Manufacture of Alternating Gradient Composite Structure of Aluminum Alloys Using Solid State Additive Manufacturing Technique

Study of Material Flow and Mechanical Properties of Friction Stir Welded AA2024 with AA7075 Dissimilar Alloys using Top-Half-Threaded Pin Tool

Improving the Quality of Dissimilar Al/Steel Butt-Lap Joint via Ultrasonic-Assisted Friction Stir Welding

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