No abstract

No abstract

The objective of the paper is an application of the model of the microstructure evolution based on three-dimensional cellular automata (CA) for hot shape rolling simulation. A short description of frontal cellular automata (FCA) is presented. The model contains two parts: the deformation and the microstructure evolution. The CA cells do not remain as undistorted cubes, but they are deformed according to the strain tensor. The independence of the grain growing from the shape and the sizes of the cell is ensured by the so-called "virtual front tracking". The microstructural part of the model simulates two phenomena: the nucleation and the growth of nuclei. There are three issues considered in the paper: the creation of the initial microstructure, the recrystallization and the phase transformation. When recrystallization is simulated, the nucleation and the grain boundary migration depend on the deformation parameters such as: the temperature, the strain, the strain rate, the dislocation density and the crystallographic orientation. The nucleation during the phase transformation is a function of the cooling rate and the final microstructure. These phenomena along with the deformation can be modeled over a wide range of multi-stage deformation processes. The process of shape rolling is chosen as an example. The data needed for the FCA calculations is received from the modeling by the finite element method. The results of the simulation of the microstructure evolution, during the last three passes of the round bars rolling with the consequent phase transformation, are presented in the paper.

The paper presents three-dimensional frontal cellular automata (FCA) based model for modeling of microstructure evolution during technological processes. It is hierarchical system. The first level is FCA, the second level is modules of microstuctural phenomena; and the third level is models of technological processes. The phase transformation module (PTM) is one of the components of the second level. PTM will contain several models of phase transformation; one of them presents transformation of austenite into ferrite and perlite. This phase transformation controlled by diffusion is considered as the nucleation and the growth of grains of other phases. The nucleation algorithm is presented in the paper. An effect of nucleation sites on final microstructure was studied on three extreme nucleation variants: nucleation on the boundaries, on the edges and in the grain corners. Simulations have been carried out for low cooling rate and relatively long time of the holding at appropriate temperature. The simulation results of the microstructure evolution studies are presented in the paper.

This paper presents a three-dimensional frontal cellular automaton (FCA)based model for modelling of microstructure evolution during technological processes. It is a hierarchical system. The first level is the FCAs, the second level contains modules of microstructural phenomena and the third level is presented by the models of technological processes. The module of the initial microstructure (IM) is one of the components of the second level. The IM allows one to obtain a digital material representation of given parameters, which can be used by other modules for further simulation. The parameters that must be assured by the IM module are the following: shape of the grains and distributions of the grain size, crystallographic orientation and boundary disorientation angles.To obtain the required parameters, the FCAs are first used as a tool for the creation of the basic microstructure characterized by the shape of the grains. The grain size distribution is obtained by the method, which changes nucleation and grain growth conditions. After the creation of the microstructure, crystallographic parameters are established. Distribution of the crystallographic orientation and boundary disorientation angles can be obtained independently or as associated parameters. Some examples of microstructures obtained by the IM module are presented in this paper.