Texture Development and Dynamic Recrystallization in AA5083 During Superplastic Forming at Various Strain Rates

摘要

Texture development in AA5083 during superplastic forming has been studied at strain rates varying from 0.0005/s to 0.3/s. As shown previously in the literature, a random texture is maintained at slower strain rates (grain boundary sliding), while at the higher strain rates, a fiber texture develops (dislocation creep). At the higher strain rates (>0.03/s), dynamic recrystallization is observed in the necked region of the sample prior to failure. This results in a dramatic transition from very fine grains (approx 10 mu m) to large grains (>100 mu m) at a critical strain. At strains above this critical level the grain size gradually decreases with increasing strain. The effect of temperature, strain rate, and constituent particle distribution on the extent and character of the recrystallized region is described. The results are explained in terms of critical strain recrystallization phenomena.