Non-uniform Grain Boundary Migration During Static Recrystallization: A Cellular Automaton Study

Abstract

During static recrystallization, grains often have non-constant and non-uniform growth rates, significantly affecting the recrystallization kinetics and the microstructure after recrystallization. A cellular automaton model was employed in order to evaluate the relative influences of gradients of stored energy, grain boundary curvature, and heterogeneity of grain boundary mobility on the non-uniform migration of grain boundary segments, leading to the formation of protrusions and retrusions. Electron back-scatter diffraction measurements of a cold-rolled copper microstructure served to feed the model. Orientation maps obtained after partial recrystallization were used to assess the model outcome. The model was capable to predict the shapes of recrystallized grains with retrusions and protrusions. Effects of different model assumptions were compared to reveal individual contributions of different factors to grain size distribution, grain shape and boundary roughness. The model predicted a decreasing average grain growth rate as a result of the progressive immobilization of an increasing fraction of grain boundary segments. The model prediction was compared with experimental results, explaining the origin of stationary boundaries and indicating some further improvements necessary to reach quantitative agreement. Graphical Abstract

Computationally Efficient Cellular Automata‐Based Full‐Field Models of Static Recrystallization: A Perspective Review

“…[125] While all the driving forces affect the overall kinetics, the grain boundary curvature plays an important role during the recrystallization, mostly for highly deformed microstructure, e.g., after rolling. [124] The situation changes dramatically when the grain growth after recrystallization is also simulated. In this case, the appropriate grain boundary curvature model is important.…”

“…Examples of the results obtained by the robust CA model developed in refs. [118,124] based on the above-presented assumptions are presented in Figure 9.…”

“…It is also well known that recrystallized grains grow faster into the neighboring regions with higher misorientation values. That is why the CA SRX models also consider the influence of crystallographic orientation in the form of Euler angles [ 124 ] or directly by the value of the misorientation between the two grains. [ 125 ] While all the driving forces affect the overall kinetics, the grain boundary curvature plays an important role during the recrystallization, mostly for highly deformed microstructure, e.g., after rolling.…”

“…[ 125 ] While all the driving forces affect the overall kinetics, the grain boundary curvature plays an important role during the recrystallization, mostly for highly deformed microstructure, e.g., after rolling. [ 124 ]…”

“…A lot of similar research dedicated to the simulation of material morphology evolution during SRX by the CA method can be found in the recent scientific literature. [ 138–142 ] Moreover, different papers were dedicated to a wide range of materials [ 143 ] including, e.g., aluminum, [ 125 ] copper, [ 124 ] low‐carbon steel, [ 109 ] Ni‐based superalloy, [ 144 ] TRIP steel, [ 145 ] or ferritic–pearlitic steel. [ 146 ] In addition, interactions between different phenomena, e.g., phase transformations and recrystallization, can also be recreated (see the case study for DP steels annealing cycle).…”