A recently developed friction self-piercing riveting(F-SPR)technique based on the combination of fric-tion stir processing and riveting has been reported to possess both solid-state bonding and mechanical fastening characteristics.However,there is still a lack of quantitative understanding of the hybrid en-hancement mechanism,hindering its engineering application.To fill in this gap,the current research investigated the microstructure evolution,microhardness distribution,and miniature-tensile performance of the aluminum alloy AA7075-T6 F-SPR joints by experiments.An accurate numerical simulation model was established to quantitatively evaluate the individual contributions of microstructure,local bonding strength,and macro interlocking to the performance of the joint,which could well explain the experi-mental results.It was found that due to the friction stirring of the rivet,solid-state bonding driven by dynamic recrystallization is realized between the trapped aluminum in the rivet cavity and the bottom aluminum sheet.The solid-state bonding zone has 75％yield strength,81％ultimate tensile strength,and 106％elongation compared to the base material.This solid-state bonding enables the internal interlock-ing between the trapped aluminum and the rivet to withstand the additional load,which forms a novel dual-interlock fastening mechanism and increases the peak cross-tension force by 14.3％compared to the single-interlock joint.

Shanghai Key Laboratory of Digital Manufacture for Thin-walled Structures,School of Mechanical Engineering,Shanghai Jiao Tong University,Shanghai 200240,China;Joining and Welding Research Institute,Osaka University,Osaka 567-0047,Japan;State Key Laboratory of Mechanical System and Vibration,School of Mechanical Engineering,Shanghai Jiao Tong University,Shanghai 200240,China

[1]Yunwu Ma;Bingxin Yang;Shanqing Hu;He Shan;Peihao Geng;Yongbing Li;Ninshu Ma-.Combined strengthening mechanism of solid-state bonding and mechanical interlocking in friction self-piercing riveted AA7075-T6 aluminum alloy joints)[J].材料科学技术（英文版）,2022(10):109-121

riveted,riveting,fastening,rivet,interlock

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