Localization of plastic flow at dynamic channel angular pressing

The effect of plastic flow localization, which is significant for obtaining ultra-fine-grain metals by intense high-rate plastic straining, is studied numerically. Large-scale localization of plastic flow, which is determined by the geometry of the problem, as well as microscopic localization appearing due to instability of plastic strain during the passage of a shock wave through the material, is detected. This effect is proposed for explaining the formation of nanocrystal-size grains obtained in experiments on dynamic channel-angular pressing.