Modeling Solidification Microstructures of Steel Round Billets Obtained by Continuous Casting

The knowledge of the position of the columnar to equaxial transition (CET) is of paramount importance to evaluate the internal quality of continuous casting (CC) products. One way to control the operational CC conditions with the objective of assuring a given quality level is to develop a numerical program able to calculate the local solidification rate (R), the local thermal gradient (G) and the local time of solidification (tf) and to relate these parameters to the CET by means of a predictive model. In the present investigation, the dendritic morphology and the CET transition of three round billets made of a low carbon steel (0.14%C) and produced by CC are characterized, and a computer model is developed to evaluate the R, G and tf-parameters. Referencing the well-known CET transition model developed by Hunt, a simple pre- diction equation is thus obtained for the steel under study and it is used to propose guidelines for the optimization of the CC operational parameters.