Microstructure and Mechanical Properties of Dissimilar Friction Stir Welding between Ultrafine Grained 1050 and 6061-T6 Aluminum Alloys

Abstract

Abstract:The ultrafine grained (UFGed) 1050 Al plates with a thickness of 2 mm, which were produced by the accumulative roll bonding technique after five cycles, were friction stir butt welded to 2 mm thick 6061-T6 Al alloy plates at a different revolutionary pitch that varied from 0.5 to 1.25 mm/rev. In the stir zone, the initial nano-sized lamellar structure of the UFGed 1050 Al alloy plate transformed into an equiaxial grain structure with a larger average grain size due to the dynamic recrystallization and subsequent grain growth. However, an equiaxial grain structure with a much smaller grain size was simultaneously formed in the 6061 Al alloy plates, together with coarsening of the precipitates. Tensile tests of the welds obtained at different welding speeds revealed that two kinds of fracture modes occurred for the specimens depending on their revolutionary pitches. The maximum tensile strength was about 110 MPa and the fractures were all located in the stir zone close to the 1050 Al side.

Friction Stir Welding of Dissimilar Aluminum Alloy Combinations: State-of-the-Art

“…It is therefore necessary to select the appropriate combination of tool rotation and welding speed for a defect free joint with a good metallurgical bond and mechanical properties. As it can be seen in Table 1, quite a lot of papers have focused on the optimization of these parameters for different combinations of Al alloys [23,29,32,33,35,36,41,42,50,54,55,58,64,80]. welding speed for a defect free joint with a good metallurgical bond and mechanical properties.…”

“…In summary, hardness distribution in the dissimilar material joints is closely associated with mechanical behavior such as strain hardening and the fracture origin. (a) AA6061-AA1050 [42] (b) AA2024-AA6061 [22] (c) AA2024-AA5083 [91] (d) AA2219-AA5083 [60] (e) AA6061-AA7075 [46] (f) AA6061-AA7075 T6 [51] Figure 10. Hardness distribution along the cross section of the dissimilar Al combination joints.…”

Advances in Welding Metal Alloys, Dissimilar Metals and Additively Manufactured Parts

“…Sun et al have presented a metallurgical and mechanical characterization of 2 mm thick 6061-T6 Al alloy plates [30].…”

Influence of Process Parameters on the Vertical Forces Generated during Friction Stir Welding of AA6082-T6 and on the Mechanical Properties of the Joints

“…Furthermore, under suitable process conditions, FSW can allow the obtaining of a microstructure able to provide mechanical properties much higher than those of most fusion welding processes and formability levels so high that post-welding forming processes of welded blanks can be performed. Because of these advantages, FSW can be very useful both in joining materials with poor weldability or that are un-weldable, such as aluminium and magnesium alloys, and in the obtaining of joints characterised by high efficiency [1][2][3][4][5][6][7][8][9][10][11].…”