Etude de l’influence de l’anisotropie sur la recristallisation et la croissance des grains.

Abstract

The present study is a contribution to understanding and modeling the microstructural mechanisms that control the changes in the crystallographic texture during recrystallization and grain growth. Our aim is to determine the characteristics that allow the following of texture evolutions and identifying the fundamental mechanisms that govern this evolution, in order to model the normal grain growth stage, in IF steel. The comparison of grain growth simulation results with the experimental behavior requires initial data for the model development and final data for its validation. For this, a detailed experimental study was performed of primary recrystallization grain growth stages, starting from 75% rolled state. We characterized the crystallographic texture, global by XRD and local by EBSD, in parallel of following the recrystallized fractions, the grain sizes and misorientations distributions and the kinetics of recrystallization and grain growth. For the simulation of normal grain growth, a modified version of the Monte Carlo technique was implemented. An original concept, using a consideration of an adjustable effect of grain size, has been introduced. This concept is based on the role of certain subpopulations of grains in the control of the final texture. It allows not only better account for the pressure at the grain boundaries but also accelerates significantly large calculations. The introduction of such grain size parameter allows to control the growth kinetics and generates the parabolic law (n = 2), predicted by theory. In addition, the self-similarity of the distribution of grain sizes is preserved and the distributions obtained are in agreement with the experimental observations. In all simulations, the intensity of the component {111} <110> increases and reaches a level that corresponds to the experimental reality. The intensity of component {111} <112> increases slightly in all calculations, which opposes to the experimental trend which provides a slight decrease of this component. It should be noted that the introduced grain size parameter has a very limited effect on the texture evolution in our model.