Effect of rolling process on fatigue performance of stir zone of AA6061 DS-FSW joint
Chengchao Du a*, Qiuhong Pan a*, Shujin Chen b, Shuang Tian c
a School of Material Science and Engineering, Jiangsu University, Zhenjiang, 212013, China
b School of Material Science and Engineering, Jiangsu University of Science and Technology, Zhenjiang, 212013, China
c School of Material Science and Engineering, Southeast University, Nanjing, 211189, China
* Corresponding author. E-mail address: dccmaterials@ujs.edu.cn, lanshanchimu@126.com, Tel: +086 18362890599 (Chengchao Du); E-mail address: panhong9004@163.com, Tel: +086 13775539039 (Qiuhong Pan).
Abstract: Stir zone (SZ) of AA6061-T6 double-side friction stir welding (DS-FSW) joint with a thickness of 6 mm had a poor fatigue performance compared with that of base metal (BM). The rolling process was employed to improve the fatigue performance of SZ. The results showed that rolling process increased the dislocation density in SZ and remarkably enhanced its fatigue performance. The crack initiation played a key role in the fatigue performance of SZ. It relied on the debonding of lamellar structure in SZ. The debonding of lamellar structure depended on the cracking of fine grain layer in lamellar structure.
Keywords: Fatigue; Friction stir welding; Rolling; Lamellar structure; Fracture