The fine grain and narrow HAZ were found in friction stir weld and the dynamic recrystallization produces fine grain.

焊核区由于动态再结晶具有细小的等轴晶粒，旁边存在一个特殊的组织形貌——热机影响区域。

youdao

And,friction stir welding uses fewer workers at less cost than other methods.

VOA: special.2009.12.30

Friction stir welding is at least twice as strong and 20 times as fast as hand-riveting.

FORBES: Ready for Takeoff