The decrease in ductility is mainly due to the cell dislocation substructure distri-buted inhomogeneously and the hardening of precipitates free zones at grain bound-aries caused by prior cold deformation.

• 预先冷形变造成不均匀分布的胞状位错结构及晶界无沉淀带加工硬化,乃是导致塑性下降的主要原因。