Microstructural evolution in friction self-piercing riveted aluminum alloy AA7075-T6 joints  

作　　者：Yunwu Ma Sizhe Niu Huihong Liu Yongbing Li Ninshu Ma 

机构地区：[1]Shanghai Key Laboratory of Digital Manufacture for Thin-Walled Structures,School of Mechanical Engineering,Shanghai Jiao Tong University,Shanghai,200240,PR China [2]State Key Laboratory of Mechanical System and Vibration,School of Mechanical Engineering,Shanghai Jiao Tong University,Shanghai,200240,PR China [3]Joining and Welding Research Institute,Osaka University,Osaka,567-0047,Japan

出　　处：《Journal of Materials Science & Technology》2021年第23期80-95,共16页材料科学技术（英文版）

基　　金：financial support of the National Natural Science Foundation of China(Grant Nos.52025058 and U1764251);the National Key Research and Development Program of China(Grant No.2016YFB0101606-08);Shanghai Jiao Tong University;financially supported by Project to Create Research and Educational Hubs for Innovative Manufacturing in Asia,Joining and Welding Research Institute,Osaka University。

摘　　要：Friction self-piercing riveting(F-SPR)is an emerging technique for low ductility materials joining,which creates a mechanical and solid-state hybrid joint with a semi-hollow rivet.The severe plastic deformation of work materials and localized elevated temperatures during the F-SPR process yield complex and heterogeneous microstructures.The cut-off action of the work materials by the rivet further complicates the material flow during joint formation.This study employed the F-SPR process to join AA7075-T6 aluminum alloy sheets and systematically investigated the microstructural evolutions using electron backscatter diffraction(EBSD)techniques.The results suggested that as the base material approached the rivet,grains were deformed and recrystallized,forming two distinct fine grain zones(FGZs)surrounding the rivet and in the rivet cavity,re s pectively.Solid-state bonding of aluminum sheets occurred in the FGZs.The formation of FGZ outside the rivet is due to dynamic recrystallization(DRX)triggered by the sliding-to-sticking transition at the rivet/sheet interface.The FGZ in the rivet cavity was caused by the rotation of the trapped aluminum,which created a sticking affected zone at the trapped aluminum/lower sheet interface and led to DRX.Strain rate gradient in the trapped aluminum drove the further expansion of the sticking affected zone and resulted in grain refinement in a larger span.

关 键 词：Friction self-piercing riveting Semi-hollow rivet Aluminum alloy Affected zone Dynamic recrystallization 

分 类 号：TG938[金属学及工艺—钳工工艺] TG146.21[一般工业技术—材料科学与工程]