The metallurgical flow sheet of steel Q345E (/% ： 0. 13 ~0. 17C

0.24 - 0.28Si

1. 02 ~ 1. 40Mn

0. 015 ~ 0

040Al

≤0. 015P

≤0. 015S) is 70 t converter-LF-VD- Φ600 mm round bloom casting process. By simulated calculation on solidification in condition with secondary cooling water ratio 0. 08 L/kg and casting speed 0. 18

0

20 and 0. 22 m/min and combined with pin-shooting test in conditions of casting speed 0. 22 m/min

liquid overheating extent 20 °C

mold cooling rate 4 600 l/min (water temperature difference between inlet and outlet 2. 7℃)

secondary cooling water rate L

1

-38

1

2

-6 and L

3

-5 L/min

the position of end of liquid core- dis

tance from meniscus 22. 4 m for Φ600 mm round bloom of steel Q345E with the casting speed is defined and based on this test the carbon macro-segregation of heavy round bloom improves obviously by application of optimized M-EMS \ (final) F-EMS combined electro-magnetic stirring (EMS) technology and adjustment of casting process. Results show that casting liquid overheating extent and EMS parameters are important factors to influence the carbon segregation of bloom ； with overheating extent 20 ~ 30℃ ，casting speed 0. 22 ~0. 24 m/min

M-EMS 200 A

2 Hz and F-EMS 400 A

8 Hz alternative stirring

the extreme difference of carbon content in steel Q345E at cross section of Φ600 mm round bloom is below 0. 04% C.