“…The plunging and dwelling stages of the FSW process were realized under position control mode, the traverse stage of FSW process was produced under force control mode. Parameters were chosen based on literature reviews [3,13,22] and previous studies [31]. The regime FSW-2 with the highest values of the total heat input and linear energy and the best mechanical performance (will be explained in detail in the part 3.1) was chosen for the impulse force implementation.…”
Section: Friction Stir Welding and Impulse Friction Stir Welding Proc...mentioning
confidence: 99%
“…The mechanical impulse is de ned by the impulse force amplitude (ΔF z , kN) and frequency (ν, Hz). Considering the properties of age-hardening aluminum alloys, the additional heat and deformation effects generated by the impulse are believed to contribute to the microstructural evolution and enhance the precipitation behavior in the joint [30][31][32].…”
Joining procedure for aluminum alloy 7075-T6 (AlZnMgCu1.5) sheets was realized by Impulse Friction Stir Welding (IFSW) with different impulse frequencies. The additional mechanical impulses during IFSW enhance the forging action of the tool, resulting in the weld microstructure modi cation. The microstructural evolution in different zones of the weld was studied, focusing on the strengthening precipitation behavior of the welded joint as well as the overall mechanical properties. The results illustrate that the application of impulses during IFSW accelerates the reprecipitation and dynamic recrystallization processes, which lead to the formation of strengthening precipitates and the homogeneous grain microstructure, respectively, in the SZ. HAZ of the welds obtained by the FSW and IFSW represent dislocation free grains interior. The precipitation content in the HAZ of the welds obtained by conventional FSW and IFSW is completely different. The HAZ of the weld obtained by conventional FSW represent high concentration of stable η phase. Conversely, high concentrations of heat sensitive phase -η' precipitates -were found in the HAZ microstructure of the joints obtained by IFSW.
“…The plunging and dwelling stages of the FSW process were realized under position control mode, the traverse stage of FSW process was produced under force control mode. Parameters were chosen based on literature reviews [3,13,22] and previous studies [31]. The regime FSW-2 with the highest values of the total heat input and linear energy and the best mechanical performance (will be explained in detail in the part 3.1) was chosen for the impulse force implementation.…”
Section: Friction Stir Welding and Impulse Friction Stir Welding Proc...mentioning
confidence: 99%
“…The mechanical impulse is de ned by the impulse force amplitude (ΔF z , kN) and frequency (ν, Hz). Considering the properties of age-hardening aluminum alloys, the additional heat and deformation effects generated by the impulse are believed to contribute to the microstructural evolution and enhance the precipitation behavior in the joint [30][31][32].…”
Joining procedure for aluminum alloy 7075-T6 (AlZnMgCu1.5) sheets was realized by Impulse Friction Stir Welding (IFSW) with different impulse frequencies. The additional mechanical impulses during IFSW enhance the forging action of the tool, resulting in the weld microstructure modi cation. The microstructural evolution in different zones of the weld was studied, focusing on the strengthening precipitation behavior of the welded joint as well as the overall mechanical properties. The results illustrate that the application of impulses during IFSW accelerates the reprecipitation and dynamic recrystallization processes, which lead to the formation of strengthening precipitates and the homogeneous grain microstructure, respectively, in the SZ. HAZ of the welds obtained by the FSW and IFSW represent dislocation free grains interior. The precipitation content in the HAZ of the welds obtained by conventional FSW and IFSW is completely different. The HAZ of the weld obtained by conventional FSW represent high concentration of stable η phase. Conversely, high concentrations of heat sensitive phase -η' precipitates -were found in the HAZ microstructure of the joints obtained by IFSW.
“…Therefore, an enhancement in the traverse speed of FSW on thick 7XXX Al alloy is greatly needed to improve the joint performance of thick workpieces of 7XXX Al alloys. Figure 1 Traverse speed vs. plate thickness during friction stir welding of 7XXX aluminium alloys, and data obtained from literature and current work [11–27]. …”
Section: Introductionmentioning
confidence: 99%
“…Traverse speed vs. plate thickness during friction stir welding of 7XXX aluminium alloys, and data obtained from literature and current work [11–27]. …”
To substantially reduce the cost of extracting petroleum from ultra-deepwater sources, manufacturing risers from 7175 aluminium (Al) alloys rather than steels is being considered. Friction stir welding (FSW), a solid-phase joining technique, is widely applied to 7XXX Al alloys because its mechanical properties are retained within the nugget zone. And, the primary technical objective of the current study is the development of high-strength, corrosion-resistant weldments that connect 7175 Al riser flanges and pipes. However, as the welding thickness increases, the welding speed can be greatly impeded, which lowers the manufacturing efficiency and weakens the mechanical properties in the heat affected zone (next to the nugget). Therefore, obtaining high-performance thick plate 7175 Al alloy joints via FSW is challenging. To overcome this dilemma, the current work optimises the tool design and welding parameters for achieving high-performance joints between 25.4 mm thick 7175 Al alloy plates in butt joint configuration.
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