纯铝粉末多孔材料等通道转角挤压数值模拟及实验

采用体积可压缩刚粘塑性有限元法,对纯铝粉末多孔烧结材料的等通道转角挤压过程进行数值模拟,获得了挤压过程试件内部变形场、静水应力场及相对密度场的分布。研究结果表明,等通道转角挤压对粉末多孔材料具有强烈的致密效果。分析认为,挤压过程所提供的高静水压力状态和大剪切变形,是孔隙得以有效焊合的关键。对纯铝粉末烧结材料进行的实验结果表明,试样经过一次挤压后,主要变形区组织剪切变形特征明显,内部的孔隙基本闭合,组织明显细化,材料的力学性能显著提高。

Numerical simulation and experimental study on the pure aluminum with porosity during equal channel angular extrusion process

The densification and deformation behavior of sintered pure aluminum during the equal channel angular extrusion (ECAE) process was investigated by compressible rigid-viscoplastic finite element method. Based on numerical results, the distribution of strain, hydrostatic stress and relative density of specimen were obtained. Results showed that ECAE process was a useful tool to eliminate porosities. Finite element analysis showed the high hydrostatic stress state and large plastic shear strain value offered by the ECAE process was the main factor for this. Experimental results showed that the microstructure of specimen had evident shearing deformation character and almost with no porosities after one pass, and the grain size became much finer and mechanical properties were improved greatly.