LAUSR

The interaction of Ti–O clusters with one another and with the surrounding steel melt results in changes in size and shape, which affect strength and hardness in the finished steel. We used MD simulation with two parameters that, together, describe the structure evolution of Ti–O clusters. These are: (1) the radius of pair gyration R¯g,p , which reflects the degree of the compactness of the cluster, and (2) the radial distribution function, which identifies the type of titanium oxide. The R¯g,p value, which is inversely related to compactness, increases with the growth of clusters, then decreases abruptly when transformation occurs. Once the clusters form a particular TiO x , the R¯g,p value remains stable until next transformation. The growth of Ti–O clusters in molten iron is divided into three stages: unstable clusters → amorphous TiO structure → amorphous Ti3O5 structure. The mean critical size for the formation of amorphous TiO structure is about 7.0 Å × 9.6 Å × 21.6 Å. The critical size for the transformation of amorphous Ti3O5 structure is about 8.4 Å × 11.0 Å × 36.0 Å.