Effect of Residual Aluminum Thickness on Microstructure and Strength of Friction Stir Spot Welded Aluminum Alloy/Copper Lap Joint

Abstract:

Dissimilar metal lap joining of A5052 aluminum alloy plate and C1100 pure copper plate was performed by using friction stir spot welding. The rotating welding tool, which was composed of a probe part and a shoulder part, was plunged from the aluminum alloy plate which was overlapped on the copper plate, and residual aluminum alloy thickness under the probe part of the welding tool after plunging of the welding tool was controlled in the range from 0 mm to 0.4 mm. The strength of the welding interface was evaluated by using tensile-shear test. Microstructure of the welding interface was examined by using an optical microscope and a field emission scanning electron microscope. The welding was achieved at the residual aluminum alloy thickness under the probe part of the welding tool below 0.3 mm. The welded area was formed at aluminum alloy/copper interface located under the probe part of the welding tool, and its width increased with decreasing the residual aluminum alloy thickness. A characteristic laminate structure was produced in the copper matrix near the welding interface. In the joint fabricated at the residual aluminum alloy thickness below 0.1 mm, hook of Cu was formed at edge of the welded area. The fracture did not occur at the welding interface. A remarkable improvement in strength was observed in the joint fabricated at the residual aluminum alloy thickness below 0.1 mm. The formation of laminate structure and hook is considered to result in joint strength improvement.

• Periodical: Materials Science Forum (Volume 1042)
• Pages: 3-8
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.1042.3
• Online since: August 2021
• Authors: Mitsuhiro Watanabe*, Shinpei Sasako
• Keywords: Aluminum Alloy, Copper, Friction Stir Spot Welding, Microstructure, Strength

References

[1] M. Abbsi, A. Karimi Teheri, M.T. Salehi, Growth rate of intermetallic compounds in Al/Cu bimetal produced by cold roll welding process, J. Alloy. Compd. 319 (2001) 233−241.

DOI: 10.1016/s0925-8388(01)00872-6

[2] G. Li, L. Zhou, W. Zhou, X. Song, Y, Huang, Influence of dwell time on microstructure evolution and mechanical properties of dissimilar friction stir spot welded aluminum-copper metals, J. Mater. Res. Technol. 8 (2019) 2613−2324.

DOI: 10.1016/j.jmrt.2019.02.015

[3] H. Badarinarayan, Q. Yang, S. Zhu, Effect of tool geometry on static strength of friction stir spot-welded aluminum alloy, Int. J. Mach. Tools Manuf. 49 (2009) 142−148.

DOI: 10.1016/j.ijmachtools.2008.09.004

[4] S. Bozzi, A.L. Helbert-Etter, T. Baudin, V. Klosek, J.G. Kerbiguet, B. Criqui, Influence of FSSW parameters on fracture mechanisms of 5182 aluminium welds, J. Mater. Process. Technol. 210 (2010) 1429−1435.

DOI: 10.1016/j.jmatprotec.2010.03.022

[5] X. Song, L. Ke, L. Xing, F. Liu, C. Huang, Effect of plunge speeds on hook geometries and mechanical properties in friction stir spot welding of A6061-T6 sheets, Int. Adv. Manuf. Technol. 71 (2014) 2003−(2010).

DOI: 10.1007/s00170-014-5632-y

[6] K. Suzuki, S. Kumai, H. Sato, K-J. Lee, T. Ookawa, A. Sato, Microstructure in Friction Stir Welded SPCC/6022 Aluminum Alloy Joints, Proc. 9th International Conference on Aluminum Alloys (2004) 873−877.

[7] M. Watanabe, T. Ookawa, S. Kumai, Formation of laminate structure at the friction stir weld interface of aluminum alloy/steel lap joint, J. Japan Institute of Light Metal 57 (2007) 536−541.

DOI: 10.2464/jilm.57.536