Coordinating optimisation of F-EMS and soft reduction during bloom continuous casting process for special steel

To control the halfway cracks and shrinkage cavities during bloom continuous casting (CC) process, final electromagnetic stirring (F-EMS) and soft reduction techniques have been coordinately optimised. The halfway crack and shrinkage cavity can be successfully controlled by adopting the CC technique parameters described as follows: (1) casting speed is 0.62 m min-1, (2) secondary cooling water ratio is 0.2 L kg⁻¹, (3) reduction amount is 18 mm; (4) reduction region ranges from 19.9 m (location of M3 roller) to 25.4 m (location of M9 roller) distance from meniscus; and (5) corresponding distributions of reduction amount for each roller are 1, 1, 2, 3, 4, 4, and 3 mm along the casting direction. As compared to origin scheme for bearing steel, the difference between the maximum and minimum segregation degrees at the strand centre can be reduced from 0.35 to 0.09 under the optimal case.