纯铝等径角挤扭新工艺变形

Research on the new process of equal channel angular pressing and torsion of pure aluminum

等径角挤扭(ECAPT)是结合等径角挤压(ECAP)和挤扭(TE)两种典型的大塑性变形(SPD)工艺而产生的一种新型细晶材料制备技术。利用刚塑性有限元技术对纯铝1100ECAPT工艺变形特征进行模拟研究,获得了等效应变和等效应力的大小及分布规律,分析了挤压载荷随变形时间的变化规律及其对试样变形的影响。结果显示,在模具拐角和螺旋通道处,等效应变得到有效积累,最终呈层状分布,且相对较为均匀,应变分布均匀性也得到一定改善,等效应力在上述两处区域达到最大。采用纯铝进行室温3道次ECAPT实验,测量试样显微组织和力学性能的变化。结果表明,实验结果与模拟结果具有较好的一致性;晶粒得到了明显细化,屈服强度、抗拉强度与显微硬度等力学性能得到明显提高,但试样塑性略有降低。

Equal Channel Angular Pressing and Torsion（ECAPT） is a new technique for preparing bulk ultrafine-grained materials,which integrates two typical severe plastic deformation methods named Equal Channel Angular Pressing（ECAP） and Twist Extrusion（TE）.The rigid-plastic FEM was used in the numerical simulation of ECAPT of aluminum1100.During ECAPT process,the distribution of effective strain and stress of the sample were obtained,the variation of load with time and its influence on the deformation were investigated.The results show that the strain is effectively accumulated,its distribution is layered and relatively uniform,the peak value of effective stress occurs in the corner and the twist channel.The experiments on pure aluminum at room temperature with 3 passes ECAPT were carried out and the evolvement of microstructure and mechanical properties of the sample were measured.It is confirmed that the simulation has good consistency with the experimental results.From the result,we realize that the microstructure is obviously refined;the mechanical properties such as yield strength,tensile strength and micro hardness are improved,but the specific elongation is declined.