AZ31B镁合金双道次热变形过程流变应力特征模拟研究

Simulation of Flow Stress Characteristic During Two-stage Hot Deformation Process in AZ31B Magnesium Alloy

建立了一类镁合金双道次热变形过程的二维元胞自动机模型。考虑到镁合金具有六重对称的密排六方晶体结构,模型采用了六边形元胞网格。另外,通过计算位错密度演变和设定晶粒形核长大规则,模型将热变形过程中动态再结晶、静态回复、静态再结晶、亚动态再结晶和晶粒长大等单个物理过程耦合到一起。为了验证模型,将其应用到AZ31B镁合金单道次和双道次热压缩过程。探讨了不同变形温度、应变速率、道次间隔和预应变对应力-应变曲线的影响。将计算结果和实验结果进行了对比,吻合较好。

A 2-D CA model has been developed to simulate two-stage hot deformation processing of magnesium （Mg） alloy. Based on the fact that Mg has an HCP crystal structure with six-fold symmetry, the model employs hexagonal CA lattice. The physically-based model has integrated the effects of individual metallurgical phenomena related with the hot deformation, including dynamic recrystalliza-tion （DRX） , static recovery, static recrystallization （SRX）, meta-dynamic recrystallization （MDRX） and grain growth, etc. The model is validated by simulating single-stage and two-stage hot compression tests of AZ31B. The effects of temperature, strain rate, the interval and pre-strain on stress-strain curves are investigated. The calculated results are compared with the available experimental find-ings in AZ31B Mg alloy, and the simulated results agree well with the experimental results and theoretical models.