Abstract:

Considering the real deformation process, numerical simulation of pure Al powder consolidation during multi-pass  ECAPT under different routes was carried out by using DEFORM-3D program. By comparing and analyzing the simulation results, it is indicated that route A and C are two optimal ECAPT routes, which possesse many advantages over route BA and BC in terms of increasing strain accumulation, promoting powder consolidation and improving deformation homogeneity. In addition, the experimental results of electron Backscattered diffraction(EBSD) show that bulk ultrafine grained Al with average grain size of around 0.8μm and excellent compressive strength of 123.3MPa can be produced under route A after four passes of ECAPT process, which has good consistency with numerical simulation results and confirmed the reliability of established finite element model.

Key words: equal channel angular pressing and torsion(ECAPT), powder particle, processing route, deformation uniformity

摘要：

结合实际变形过程,采用DEFORM-3D对不同变形工艺路径下纯铝粉末材料等径角挤扭(ECAPT)多道次变形过程进行了三维数值模拟。有限元模拟结果表明:A和C工艺路径可在较小的挤压载荷下实现有效的应变累积和均匀的变形分布,是两种较为理想的变形路径;BA和BC两种工艺路径虽然能够使变形材料累积的等效应变量大大增加,但却会造成试样变形分布的严重不均匀。电子背散射衍射(EBSD)实验结果表明，A路径下纯铝粉末材料经4道次等径角挤扭变形后,可获得组织均匀、性能优良的块体超细晶铝,材料平均晶粒尺寸约为0.8μm,抗压强度高达123.3MPa,验证了前述模拟结果的可靠性。

关键词: 等径角挤扭, 粉末颗粒, 工艺路径, 变形均匀性