Two-dimensional Monte Carlo-Voronoi simulation of grain growth and nucleation in the heat affected zone of TWIP-Ti welds

The microstructural simulation of grain growth and static recrystallization (SRX) phenomena were simulated in the weld heat-affected zone (HAZ) in Twinning Induced Plasticity (TWIP) steel microalloyed with Ti by means of a 2D Monte Carlo (MC) model combined with Voronoi tessellations (MC-Voronoi) based on experimental data. The simulation considered the effect of different levels of heat input for the Gas Tungsten Arc Welding (GTAW) process in the microstructural field. The MC-Voronoi model estimated the number of grains with annealing twins in TWIP-Ti steel specimens in both as-solution and post-welding conditions. Through the application of modified probabilities for both growth and recrystallization, the proposed microstructural model allowed the simulation of microstructures with lognormal and bimodal grain size distributions. The high microstructure reproducibility and grain morphology predicted by the Voronoi tessellation were improved by means of an image post-processing performed in MATLAB (R). A good agreement was obtained between experimental and microstructural simulation results; the validation process was carried out by means of grain size statistical analysis.