Limit of structure refinement for 7075 aluminum alloy at elevated temperature by hot deformation

Performance of commercial alloys can be improved greatly by severe plastic deformation, which refines grain of metals to several micrometer or sub micrometer order. During 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 12 μm, and it will not become smaller with the increase of total strain, that is to say, the limit of grain refinement is about 1 μm.