On the microstructure-strength relationship in friction-stir welds
摘要
The broad aspects of the microstructure-strength relationship in friction-stir welding (FSW) are discussed. It is shown that FSW may promote both strengthening and softening effects, and the final strength of FSW joints may be sensitive to the initial material condition. In the case of a fully-recrystallized material, FSW may lead to the hardening effect due to the grain refinement. In the case of the work- or precipitation-hardened structural conditions, FSW may result in material softening due to recrystallization or precipitation coarsening/dissolution.