镁合金管材挤压变形动态再结晶流函数法研究

为研究热挤压成形镁合金管材过程中动态再结晶现象,首先采用流函数方法建立了挤压锥杯内变形区的应变速率张量场、等效应变速率场、最小剪切应变速率场以及应变张量场等数学模型,然后通过热模拟实验测得镁合金AZ91D高温力学性能数据,计算并建立了AZ91D镁合金高温变形时发生动态再结晶的临界应变函数;结合镁合金管材挤压过程应变速率及应变场等,建立了挤压过程变形区内产生初始动态再结晶的判定准则及分布规律。最后通过经实验验证了该准则及分布规律的准确性,为实际生产工艺的制定提供了理论依据。

Study on Dynamic Recrystallization in Extrusion Forming of Magnesium Alloy Tube by Flow Function Method

To study the dynamic recrystallization of magnesium alloy tube in extrusion forming, firstly, the mathematic model of strain rate field, shear strain rate field and strain filed in extrusion cone-shape cup were built by flow function method. Then, the mechanical behavior of magnesium alloy AZ91D under high temperature was acquired by thermal com-pression experiments, as well as the critical strain function of dynamic recrystallization of AZ91D was built on the basis of experiment results. Combined with the strain rate field and critical strain function of dynamic recrystalliztion, the model of dynamic recrystallization distribution in cone-shape cup was built. Finally, this model was validated by extrusion forming experiments, which could provide theoretical evidence for the formulation process of actual production.