Abstract: Macro- and micro-structure evolution of 5182 aluminum alloy was studied in multi-directional forging (MDF) with the final forging temperatures of 340 ℃. The results showed that the fine grain zone in the center of sample expands gradually with the increment of the forging passes from 3 to 12. But increasing the forging pass to 12 can not eliminate the structure difference between the center and peripheral area. The structure of area near the forging harmers is constantly destroyed (but no distinct recrystallization occurs in the structure) with the forging pass increases from 3 to 12. When the forging pass is 3， partial recrystallization occurs on the center area of the sample. When the forging pass reaches 6， a fully recrystallization occurs in the center area of the sample， and the finest recrystallization grains are observed. With the forging pass further increases to 9 and 12， the recrystallization grains are a little coarser than that forged by 6 passes. However， the grains in the center area of the samples forged by 9 and 12 passes show the almost same size. So there is a grain refinement limitation in the center of sample with the increment of the forging passes.

Key words: multi-directional forging, 5182 Al alloy, severe plastic deformation, recrystallization