镁合金加工硬化机理及数学模型研究

发布时间：2018-05-21 15:44

本文选题：AZ31镁合金 + 加工硬化　；参考：《武汉科技大学》2015年硕士论文

【摘要】：镁合金具有密排六方晶体结构，滑移系少，室温塑性变形能力差，因此要提高镁合金的塑性，需要深入研究镁合金塑性变形的机理，而加工硬化是镁合金塑性变形的基础问题。本文系统研究了挤压态AZ31镁合金在拉伸和压缩变形过程中的加工硬化规律及产生加工硬化的原因。通过拉伸与压缩试验，研究了AZ31镁合金应力-应变曲线及加工硬化率曲线。测量了镁合金变形前后的织构，表明挤压态镁合金具有典型的0002基面织构，沿挤压方向压缩时，基面发生了转动，并产生了1012拉伸孪晶，，解释了镁合金不同方向压缩引起力学各向异性的现象。本文重点研究了第Ⅱ阶段加工硬化产生的条件及机理，结果表明：低温、高应变速率变形时，容易出现第Ⅱ阶段加工硬化。根据流变应力位错模型对第Ⅱ阶段形成原因进行了深入分析。本文深入研究了AZ31镁合金第Ⅲ阶段加工硬化规律，结果表明：第Ⅲ阶段加工硬化服从Voce定律，即加工硬化率与应力呈线性关系，根据实验结果得到了Voce定律的具体表达式。
[Abstract]:Magnesium alloy has dense hexagonal crystal structure, less slip system and poor plastic deformation ability at room temperature. Therefore, in order to improve the plasticity of magnesium alloy, it is necessary to study the mechanism of plastic deformation of magnesium alloy in depth, and work hardening is the basic problem of plastic deformation of magnesium alloy. In this paper, the rule of work hardening of extruded AZ31 magnesium alloy during tensile and compression deformation and the causes of work hardening are systematically studied. The stress-strain curve and work hardening rate curve of AZ31 magnesium alloy were studied by tensile and compression tests. The texture of the extruded magnesium alloy before and after deformation is measured. It is shown that the extruded magnesium alloy has a typical 0002 basal surface texture, which rotates along the extrusion direction and produces 1012 tensile twins. The mechanical anisotropy of magnesium alloys induced by compression in different directions is explained. In this paper, the conditions and mechanism of work hardening in the second stage are studied. The results show that at low temperature and high strain rate deformation, the work hardening in the second stage is easy to occur. Based on the rheological stress dislocation model, the causes of the formation of the second stage were analyzed. In this paper, the work hardening law of AZ31 magnesium alloy in the third stage is studied. The results show that the work hardening wear in the third stage is based on the Voce law, that is, the linear relationship between the work hardening rate and the stress. According to the experimental results, the concrete expression of the Voce law is obtained.
【学位授予单位】：武汉科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG146.22

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