Key Technologies of Macro Segregation Control in 320 mm×410 mm Continuous Casting Bloom for Railway Steel

The electromagnetic stirring,total amount of soft reduction and the matching between super heat and casting speed were researched in order to control carbon segregation index of transverse section and center segregation in rail steel bloom. The key technologies of segregation control in 320 mm×410 mm continuous casting bloom for railway steel had been established. The best parameters for continuous casting rail steel from this investigation are as follows: intensity and frequency of mold electromagnetic stir current are 600 A and 2.4 Hz,intensity and frequency of final electromagnetic stir current are 330 A and 7 Hz,total reduction of soft reduction is ranged from 9 mm to 12 mm,superheat is ranged from 20 ℃ to 35 ℃ and the casting speed is ranged from 0.70 m/min to 0.72 m/min. Based on these parameters,the resulted bloom has a high quality where the center equiaxial crystal is 41.2% on average,the rate of center segregation less than 0.5 is 85%,and the carbon segregation index of transverse section ranges from 0.95 ~1.07. The quality of bloom meets the standard requirements for rail production.