Progressive micro-scaled deformation is an efficient approach to fabricating microparts directly using metal sheets. However, how the size effect and material crystal structure affect the deformation of metallic materials in the deformation process has not yet been well understood. In this research, a progressive micro-scaled deformation of metallic materials with different crystal structures and grain sizes was conducted to realize a multi-stage deformation and produce microparts directly using metal sheets via piercing, two step extrusion, and blanking. A unified mechanism-based constitutive model was proposed to describe the grain size dependent flow stress by incorporating dislocation glide and deformation twinning. The constitutive equations were implemented into the finite element model to simulate the progressive micro-scaled deformation. The deformation behavior of the microparts made of FCC pure copper, BCC pure iron, and HCP pure titanium with different size scales were thus extensively studied based on the material flow, strain pattern, microstructure evolution, and forming defect formation. The results show that the length of cylindrical micropin and the extrudates of the microformed parts by using FCC pure copper and BCC iron are decreased with the coarsening of grains. Deformation twins were prevalently formed in the produced micropin and micropart using HCP pure titanium with coarse grains and the dependency of their length on the initial grain size became unnoticeable. The irregular geometric defects include burr, incline, rollover, and bulge. The burr and rollover of extruded micropart are generally deteriorated with the increasing grain size for the three used materials, whereas the dimension of incline is not significantly affected by the initial grain size. All of these provide more insights into the progressive micro-scaled deformation of metallic materials for making bulk microparts.

渐进式微尺度变形是一种直接使用金属板制造微零件的有效方法。然而，在变形过程中尺寸效应和材料晶体结构如何影响金属材料的变形还没有被很好地理解。在这项研究中，对具有不同晶体结构和晶粒尺寸的金属材料进行了渐进式微观变形，以实现多阶段变形，并通过穿孔，两步挤压和落料直接使用金属板直接生产出微型零件。提出了一种基于机制的统一本构模型，通过结合位错滑移和变形孪生来描述与晶粒尺寸有关的流应力。本构方程被实施到有限元模型中，以模拟渐进式微观尺度的变形。因此，根据材料流动，应变模式，微观组织演变和形成缺陷的形成，广泛研究了由FCC纯铜，BCC纯铁和HCP纯钛制成的微零件的变形行为。结果表明，随着晶粒的粗化，使用FCC纯铜和BCC铁减少了圆柱状微针的长度和微成形零件的挤压物。使用具有粗大晶粒的HCP纯钛，在生产的微针和微零件中普遍形成变形孪晶，并且它们的长度对初始晶粒尺寸的依赖性变得不明显。不规则的几何缺陷包括毛刺，倾斜，翻滚和凸起。对于三种使用过的材料，随着微粒尺寸的增加，挤出的微型零件的毛刺和翻转通常会恶化，倾斜尺寸不受初始晶粒尺寸的显着影响。所有这些都为制造大块微零件的金属材料的渐进式微尺度变形提供了更多的见识。