Multilevel Model for Description of Material Deformation under Structural Superplasticity Conditions: Modified Kinetic Equations

摘要

It is proposed a mathematical model, describing the behavior of polycrystalline metals and alloys during deformation with transition to structural superplasticity regime. The model is constructed within the multilevel approach, based on crystal plasticity, which allows to describe explicitly changes in material structure and physical deformation mechanisms at different scale levels by introducing internal variables and their evolution equations into structure of mathematical model. Use of this approach is also promising in modeling of various deformation regimes and transitions between them. Model includes the description of main inelastic deformation mechanisms-grain boundary sliding, intragranular dislocation sliding, as well as accompanying processes-grain boundary diffusion, crystallite lattice rotations, dynamic recrystallization. The article is focused on description and physical substantiation of hardening law for grain boundary sliding, taking into account the mutual influence of basic mechanisms, and also on changing their role during inelastic deformation. The results of numerical calculations for deformation of aluminum alloy under conditions of structural superplasticity are presented: staging of stresses versus strains, observed in experiments, is shown; the role of main mechanisms and processes has been determined and analyzed at each stage.