MICROSTRUCTURE EVOLUTION DURING FRICTION-STIR WELDING OF Cu-30Zn BRASS

摘要

The triumph of friction stir welding (FSW) technology during the last decade gave rise to significantinterest to the underlying physical processes. Accordingly, microstructural and textural studies are nowone of the research hotspots in the FSW field [1]. To date, the microstructural examinations in this areawere mainly focused in aluminum alloys, i.e. materials with high stacking fault energy. The graindevelopment process in this case was found to be primarily governed by continuous recrystallization [e.g.2, 3], which typically involved transformation of low-angle boundaries (LABs) into high-angle boundaries(HABs)[4]. Recently, FSW has been also successfully applied for joining of austenitic steels [5] and Cu-30Znbrass [6], i.e. the materials with low stacking fault energy. In these alloys, dislocation mobility is relativelylow and thus the development of dislocation boundaries is difficu as a result, the continuousrecrystallization should be inhibited. On the other hand, high density of free dislocations should providelarge driving force for discontinuous recrystallization. Therefore, this mechanism is expected topredominate during FSW. To examine this idea, microstructural evolution during FSW of Cu-30Zn brasswas systematically studied in this work.