Refill Friction Stir Spot Welding Al Alloy to Copper via Pure Metallurgical Joining Mechanism

Chinese Journal of Mechanical Engineering

Wentao Hou¹  Yuquan Ding¹  Fenjun Liu²  Wenya Li³  Wei Guo³  Haiyan Chen³  Xiaochao Liu³  Adrian Gerlich³  Zhikang Shen⁴ 

[1] Centre for Advance Materials Joining, University of Waterloo, N2L 3G1, Waterloo, Canada;College of Energy Engineering, Yulin University, 719000, Yulin, China;School of Materials Science and Engineering, Northwestern Polytechnical University, 710072, Xi’an, China;School of Materials Science and Engineering, Northwestern Polytechnical University, 710072, Xi’an, China;Centre for Advance Materials Joining, University of Waterloo, N2L 3G1, Waterloo, Canada;

关键词: Refill friction stir spot welding;    Al alloy;    Copper;    Interfacial microstructure;    Mechanical properties;   

DOI  :  10.1186/s10033-021-00593-0

来源: Springer

【 摘 要 】

The current investigation of refill friction stir spot welding (refill FSSW) Al alloy to copper primarily involved plunging the tool into bottom copper sheet to achieve both metallurgical and mechanical interfacial bonding. Compared to conventional FSSW and pinless FSSW, weld strength can be significantly improved by using this method. Nevertheless, tool wear is a critical issue during refill FSSW. In this study, defect-free Al/copper dissimilar welds were successfully fabricated using refill FSSW by only plunging the tool into top Al alloy sheet. Overall, two types of continuous and ultra-thin intermetallic compounds (IMCs) layers were identified at the whole Al/copper interface. Also, strong evidence of melting and resolidification was observed in the localized region. The peak temperature obtained at the center of Al/copper interface was 591 °C, and the heating rate reached up to 916 °C/s during the sleeve penetration phase. A softened weld region was produced via refill FSSW process, the hardness profile exhibited a W-shaped appearance along middle thickness of top Al alloy. The weld lap shear load was insensitive to the welding condition, whose scatter was rather small. The fracture path exclusively propagated along the IMCs layer of Cu9Al4 under the external lap shear loadings, both CuAl2 and Cu9Al4 were detected on the fractured surface on the copper side. This research indicated that acceptable weld strength can be achieved via pure metallurgical joining mechanism, which has significant potential for the industrial applications.

【 授权许可】

CC BY