轧制镁合金板材超塑性变形时的空洞损伤行为

通过扫描电镜观察、定量分析和数学模型，研究热轧AZ31B镁合金板材超塑性变形过程中的空洞损伤演化行为。轧制AZ31B镁合金板材超塑性变形时产生空洞化现象，空洞形核于晶界处，尤其是在三叉交界处。空洞不断长大、连接是引起材料断裂的原因。空洞出现连接或聚合的同时，存在二次空洞的形核和长大。得出了AZ31B镁合金板材超塑性变形损伤材料特征参数和损伤变量临界值，为镁合金板材超塑性变形失稳、成形极限理论预测和成型工艺参数优化提供了依据。

Cavity Damage Evolvement of Magnesium Alloy Sheet During Superplastic Deformation

The cavity damage evolvement of hot-rolled AZ31B magnesium alloy sheet during superplastical deformation is investigated by SEM observation, quantitative analysis and simulation. The cavity happens while the hotrolled AZ31B magnesium alloy sheet is superplastically deformed, and the cavity starts on the grain boundary, especially on the tri-grain boundary. The continuously growing and linking of the cavities is the reason of the material damage. The secondary nucleus formation and growth of the cavity is companied with the linking and connecting. The characteristic parameters of damage evolvement and critical value of damage variables are achieved from the experiments, and the theoretical background for the prospect of superplastical deformation instability and deformation theoretical limit and optimized technical parameters of magnesium alloy sheet forming is provided.