The mechanism of grain refining in the stir zone of friction stir welded 2024 aluminum alloy

Friction stir welding (FSW) is a new solid-state welding process that can be used to weld aluminum alloys such as Al-2024 that are hard to weld by conventional fusion welding. The grain refining in the stir zone occurs during friction stir welding. The mechanism of grain refining in the stir zone is interest for researchers. The effect of rotational speed and feed speed on the grain size in the stir zone of the 2024 aluminum alloy was investigated in this study. Also the mechanism of grain refining in the stir zone identified. It is found that the grain size of the stir zone increases with the increasing of rotational speed and decreasing of feed speed during FSW. Also it was specified that the mechanism of grain refining in the stir zone is continues dynamic recrystallization (CDRX).