Computational Modeling for Coarsening of (Fe,Cr)₂B in Borated Stainless Steel

Abstract

The microstructure of borated stainless steels subjected to high temperature annealing process near solidus was confirmed using scanning electron microscopy. The spheroidization and coarsening of (Fe,Cr)₂B occurred significantly during annealing at 1200°C. The coarsening rate was much faster than that predicted by existing models due to the anisotropy of the precipitate, i.e., its non-spherical shape. We simulated the coarsening behavior in a multi-component diffusional simulation including the anisotropic effect with respect to annealing time. The model illustrated the coarsening behavior of (Fe,Cr)₂B well in borated stainless steels, and the interfacial energy between the precipitate and the austenite matrix was estimated to be 1.8 J·m⁻².

Fig. 5 Measured and simulated particle size as a function of time. (a) Blank squares represent measured particle size of B18 specimen. Dashed, dot, double dot and solid lines represent particle radii predicted by Robino’s model, LSW model, model-I and model-II, respectively. (b) Blank squares, circles and upper triangles represent measured particle size of B02, B08 and B18 specimen, respectively. Dot, dashed and solid line represent particle radii predicted by model-II for B02, B08 and B18 alloy, respectively.