论文部分内容阅读
为了分析单个晶粒变形行为对微成形的影响,将自由表面的晶粒看作单晶体构建晶体塑性模型。基于率相关晶体塑性理论,考虑试样尺寸、初始晶体取向及其分布,分析微圆柱体墩粗变形中尺寸效应机理。结果表明,流动应力随着试样尺寸的减小而明显减小,晶体取向的分布对试样流动应力具有显著影响,并随着塑性变形的进行而减小。由于单晶体的各向异性,在试样表层发生了明显的非均匀变形,这将导致表面粗糙度的增加,小尺寸试样则更加明显。过渡晶粒的存在使得晶粒各向异性对表面形貌的影响减小。模拟结果得到了实验验证,这表明所建立的模型适合于以尺寸依赖性、流动应力分散性和非均匀变形为特点的微成形工艺分析。
In order to analyze the effect of single grain deformation on micro-forming, the free surface grains are regarded as single crystal to construct the crystal plasticity model. Based on the rate-dependent crystal plasticity theory, considering the sample size, initial crystal orientation and its distribution, the size effect mechanism in the coarse deformation of the microcylinder pier is analyzed. The results show that the flow stress decreases obviously with the decrease of the sample size. The distribution of crystal orientation has a significant effect on the flow stress of the sample, and decreases with the plastic deformation. Due to the anisotropy of the single crystal, significant non-uniform deformation occurs on the surface of the sample, which results in an increase of the surface roughness and the smaller size of the sample becomes more conspicuous. The presence of transitional grains reduces the effect of grain anisotropy on the surface topography. The simulation results are verified by experiments, which shows that the model is suitable for the analysis of micro-forming process which is characterized by size dependence, dispersion of flow stress and non-uniform deformation.