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.

中文翻译：

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轧制工艺对AA6061-T6双侧摩擦搅拌焊接接头搅拌区疲劳性能的影响

与贱金属（BM）相比，厚度为6 mm的AA6061-T6双面摩擦搅拌焊接（DS-FSW）接头的搅拌区（SZ）具有较差的疲劳性能。采用轧制工艺来改善SZ的疲劳性能。结果表明，轧制过程增加了SZ中的位错密度，并显着提高了其疲劳性能。裂纹萌生在SZ的疲劳性能中起关键作用。它依赖深圳的层状结构的剥离。层状结构的剥离取决于层状结构中细晶粒层的开裂。