Friction stir processing of large-area bulk UFG aluminum alloys

Friction stir processing (FSP) was used to refine the grain size in commercial 7075 Al to a sub-micrometer scale (∼250 nm). The resulting microstructural characteristics were studied. In principle, by running multiple overlapping passes, any desired size thin sheet can be processed to an ultrafine grained microstructure (UFG) material with a relatively uniform microstructure.