Solidification behavior of continuously cast high carbon steel billets was investigated with an objective of producing high quality billets by determining the optimum final electromagnetic stirring （F-EMS） parameters. Char- acteristics of centerline segregation were analyzed for lots of billet samples collected from the plant through obtaining the carbon concentrations of drill chips, which were correlated with the operating parameters of the caster and stir- rers, but a problem occurred that segregation control results of trial billets with the same casting and stirring param- eters often have drastic fluctuations. An attempt was made to find out the induced reasons of this problem by meas uring the electromagnetic torque, analyzing the secondary dendrite arm spacing （SDAS） and the corresponding cool- ing rate of the typical specimens, and observing the longitudinal profile of etched billet samples. Then a simple dy- namic secondary cooling model was developed based on the solidified shell thickness control mode, by which the maximum carbon segregation index was reduced effectively, and thus the segregation fluctuation problem was basi- cally solved. Finally, the most favourable stirring parameters were determined as the casting speed of 1.65 m/rain, the liquid core thickness of 40 mm, stirring current of 360 A and frequency of 12 Hz.
