The micro-injection upsetting (MIU) experiments of commercially pure aluminium have been conducted on two groups of specimens with different grain structures. One group is of coarse grain (CG, undeformed) and the other group is of fine grain (FG) achieved via the 4th pass equal channel angular pressing in micro-meso/scale. The two groups were further processed by micro/meso-scale extrusion before conducting MIU for fabricating tiny pins. Micro-upsetting test of the tiny pins showed that the material has a good isotropic flow forming and is free of undesirable defects comparing with the CG counterparts, which can be ascribed to the decreasing of grain boundary strengthening effect in the case of FG structure.

对具有不同晶粒结构的两组试样进行了商业纯铝的微注射镦粗 (MIU) 实验。一组是粗晶粒（CG，未变形），另一组是细晶粒（FG），通过第 4 道次等通道角挤压在微细/尺度上实现。在进行 MIU 以制造微小的针脚之前，这两组通过微/中尺度挤压进一步加工。微小销钉的显微镦粗试验表明，该材料具有良好的各向同性流动成形性，与 CG 对应物相比，没有不良缺陷，这可以归因于 FG 结构情况下晶界强化效果的降低。