Accounting for random character of recrystallisation and uncertainty of process parameters in the modelling of phase transformations in steels

The problem of multiphase microstructure heterogeneity was considered in this paper. The stochastic model of multi-step hot deformation was applied to calculate histograms of the dislocation density and the grain size at the beginning of phase transformations. These histograms were used as input data for simulation of phase transformations using conventional deterministic modelling. Heterogeneity of the phase composition was calculated for various constant cooling rates, as well as for the industrial laminar cooling process. In the latter case, uncertainty of the boundary conditions was additionally accounted for. The results showing an influence of the heterogeneity of the dislocation density and the grain size on the microstructure heterogeneity in the final product can be considered reliable, because they are based on the material models, which were identified and verified experimentally in earlier publications. The effect of the uncertainty of the boundary conditions is presented in a qualitative manner only, and may be the subject of future research.