Microstructural characteristics and mechanical properties of bobbin-tool friction stir welded 2024-T3 aluminum alloy

Authors

Jihong Dong, Beijing University of Chemical Technology
Chong Gao, Chinalco Research Institute of Science and Technology
Yao Lu, University of WollongongFollow
Jian Han, University of WollongongFollow
Xiangdong Jiao, Beijing University of Chemical Technology
Zhixiong Zhu, University of WollongongFollow

RIS ID

112585

Publication Details

Dong, J., Gao, C., Lu, Y., Han, J., Jiao, X. & Zhu, Z. (2017). Microstructural characteristics and mechanical properties of bobbin-tool friction stir welded 2024-T3 aluminum alloy. International Journal of Minerals, Metallurgy, and Materials, 24 (2), 171-178.

Abstract

Cold-rolled 2024–T3 sheet alloy was subjected to bobbin-tool friction stir welding (BTFSW). The microstructural characteristics and mechanical properties of the nugget zone in the as-welded state were investigated. The results show that the equiaxed grain size of BTFSW 2024–T3 alloy decreases from 7.6 to 2.8 μm as the welding speed is increased from 80 to 120 mm/min; in addition, fine grains are generated in the nugget zone and the size distribution is non-uniform. All Al₂CuMg (S′) precipitates dissolve into the Al matrix, whereas Mn-rich phases confirmed as T phases (Al₂₀Cu₂Mn₃, Al₆Mn, or Al₃Mn) remain unchanged. The optimized parameters for BTFSW are verified as the rotation speed of 350 r/min and the travel speed of 100 mm/min. The variations in precipitation and dislocation play more important roles than grain size in the nugget zone with respect to influencing the mechanical properties during the BTFSW process. After the BTFSW process, the fracture mode of base material 2024–T3 alloy transforms from ductile rupture to ductile-brittle mixed fracture.