Investigation on Initiation and Development of Microscopic Inhomogeneity During Plastic Deformation of Polycrystalline Metals

许多用于工业的金属材料是多晶的，它们的变形行为在微观上是不均匀的。因此，研究非均匀材料的微观变形行为具有重要意义。为了弄清非均匀材料的变形行为，有必要研究材料的应力或应变分布、成分几何形状的影响以及材料局部微观变形与整体变形行为的关系。本研究的目的是通过实验和数值分析来阐明微观塑性变形的各种特征。硬度测试是检验材料特性的基本方法之一。通过硬度测量可以估计材料的局部特性。近年来，超显微硬度测试设备的发展使得在很小的载荷下测量硬度成为可能。结果表明，随着外加塑性应变的增加，多晶铝中各晶粒的硬度值和分散度均有所增加。对多晶铝的微观变形行为进行了讨论。结果表明，用刚塑性有限元法可以很好地模拟非均匀材料塑性变形的特征特征。

Many of the metallic materials used for industry is polycrystalline and their deformation behavior is microscopically heterogeneous. Then, it is important to study the microscopic deformation behavior of inhomogeneous material. In order to clarify the deformation behavior of inhomogeneous material, it is necessary to study the distribution of stress or strain, the influence of the geometry of the constituents and the relation between local microscopic deformation and the global deformation behavior of the material. The aim of the present study is to clarify by experiments and numerical analysis various features of microscopic plastic deformation.Hardness testing is one of the fundamental methods to examine the characteristics of materials. The local material characteristic can be estimated with the hardness measurement. Recently, the ultra-micro hardness testing equipment has been developed which makes it possible to measure the hardness with very small load. It is shown that the hardness values of respective grains in polycrystalline aluminum as well as their dispersion increase with the applied plastic strain. Discussion is made on the microscopic deformation behavior of polycrystalline aluminum.It is also shown that the characteristic feature of the plastic deformation of inhomogeneous material is well numerically simulated by the rigid-plastic finite element method.