INFLUENCES OF ALLOYING ELEMENTS ON GRAIN SIZES IN FRICTION STIR PROCESSED PURE ALUMINUM AND ALUMINUM ALLOYS

摘要

A friction stir processing (FSP) technique has been developed for use with aluminum and magnesium alloys. The microstructure was evolved into fine grains by the dynamic recrystallization during FSP. In this study, FSP was used to pure aluminum and aluminum alloys and the influence of alloying element on the grain size was investigated. In addition, the relationship between the grain size and the Zener-Hollomon parameter was investigated. There was observed difference in grain size between these materials. The recrystallized grain of FSP-ed ultra-high-purity (99.999%) aluminum was particularly large, compared to the grain sizes of other materials, when subjected to the same processing conditions. In contrast, grain sizes decreased with an increase in the Zener-Hollomon parameter in all materials. However, the grain size reached a certain minimum value at high-strain-rates of processing. Compared to other processed aluminum materials, the minimum grain size was found for each material.