Abstract:Performance of commercial alloys can be improved greatly by severe plastic deformation, which refines grain of metals to several micrometer or sub-micrometer order. Du, ring severe plastic deformation, the final size of grain structure depends on the following factors: strain rate, total strain, deformation temperature and so on. Under a certain condition, structure cannot be infinitely refined, which means that the size of grain has a limit with the increase of total strain. Under conventional hot deformation temperature, the grain size of 7075 aluminum alloy can be refined to 1-2 μm, and it will not become smaller with the increase of total strain, that is to say, the limit of grain refinement is about 1μm.

Key words:  7075 aluminum alloy; deformation refinement; ultra-fine grains