MODELING OF SUBGRAIN'S CRYSTALLOGRAPHIC MISORIENTATION DISTRIBUTION

摘要

At present the actual task of various industries is to create products from metal polycrystals and their alloys with the required properties and characteristics. The processing of such products is generally carried out with intense elastoplastic deformation, and is often accompanied by temperature effects. At the same time, the structure of materials undergoes substantial rearrangements, which leads to a significant change in their properties. An effective tool for solving the problem of creating products with the necessary characteristics is the use of multilevel elastoplastic models that allow one to investigate the internal structure of a material in numerical experiments. In the developed two-level statistical model of inelastic deformation, there is the problem of selecting (forming) heterogeneous elements (subgrains) in the initially approximately homogeneous grain. The main source of inhomogeneity is the appearance of crystallographic misorientation of parts (subgrains) of the original grains with respect to one another. The paper considers the problem of determining the orientation of subgrains in the initial stages of inelastic deformation. The mechanism of formation of incidental cell boundaries as a consequence of the appearance of dislocation walls is considered. The method to model boundaries of this type is proposed. In the reference configuration of deformation, flat sections of the cell boundaries (facets) are randomly assigned according to the uniform law. It is supposed that some of mobile dislocations "settle" on the prescribed incidental boundaries. It is shown that due to the appearance of cell boundaries the angle of the subgrain's crystallographic misorientation is proportional to the dislocation shears in the grain. Calculations are made of the uniaxial stretching of a copper polycrystal. Satisfactory agreement between numerical results of the subgrains misorientation distribution with respect to the initial grain and experimental data is shown. The model also makes it possible to take into account the decrease in the number of active slip systems in subgrains during rotation.