AZ31镁合金等通道转角挤压应变累积均匀性分析及组织性能研究

Homogeneous Deformation Analysis and Microstructure Properties Study of AZ31 Magnesium Alloy in Multi-pass Equal Channel Angular Pressing

等通道转角挤压工艺(Equal Channel Angular Pressing,ECAP)是通过剧烈塑性变形改变微观组织结构生产超细晶粒材料的材料加工方法,工件变形的均匀性一直是ECAP工艺过程中影响材料性能的主要原因之一。采用空间转换法实现了AZ31镁合金多道次ECAP挤压过程中有限元分析相关场量的准确传递,完成了四种不同挤压路径ECAP多道次挤压工艺的有限元模拟,获得了相应挤压件累积等效应变的分布规律。研究确定了经过四道次ECAP挤压以后等效应变累积最为均匀的挤压路径。通过微观组织观察和室温拉伸力学性能实验探讨了不同路径多道次ECAP挤压AZ31镁合金的组织性能变化规律。分析结果表明通过合适的变形路径可以获得细小而均匀的微观组织,当材料的应变累积均匀时,其力学性能也较好。

Equal channel angular pressing （ECAP） is an interesting method for changing microstruc- ture and producing ultra fine grained （UFG） materials through super-plastic deformation. The homo- geneous deformation is the main factor that influences the material performance during ECAP. Four processing routes are analyzed in detail by using finite element method with spatial switching method through rotating three-dimensional model in multi-pass pressing. The accumulated effective strain dis- tribution of the work-piece processed by ECAP for four pressing routes are obtained respectively through finite element simulation. The processing route that can generate more homogeneous effec- tive＇s main distribution in sample after four routes processing is defined. The mechanical property of AZ31 magnesium alloy processed by multi ECAP passes in different routes was analyzed through mi- crostructure observation and mechanical tensile test at room temperature. The experimental results show that the fine and uniform microstructure can be acquired by appropriate deformation route, the mechanical property of AZ31 magnesium alloy is greatly improved when strain accumulation uniform after ECAP processing.