Abstract: 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 L₁-38, 1₂-6 and L₃-5 L/min, the position of end of liquid core- distance 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.

摘要： Q345E钢(/%:0.13~0.17C,0.24~0.28Si,1.02~1.40Mn,0.015~0.040Al,≤0.015P,≤0.015S)的冶金流程为70 t转炉-LF-VD-Φ600 mm圆坯连铸工艺。通过0.08 L/kg比水量和0.18、0.20、0.22 m/min拉速条件下的凝固模拟计算,结合拉速0.22 m/min,过热度20℃,一冷4 600 L/min(进出水温差2.7℃),二冷L₁-38、L₂-6和L₃-5 L/min条件下的射钉试验,确定该拉速下Q345E钢Φ600 m/圆坯的凝固末端位置距弯月面22.4 m,在此基础上优化结晶器M-EMS\末端F-EMS组合电磁搅拌,调整连铸工艺,使大圆坯宏观碳偏析取得显著改善。结果表明,浇铸过热度、电磁搅拌参数是影响碳偏析的重要工艺条件;当过热度20~30℃、拉速0.22~0.24 m/min、 M-EMS(200 A,2 Hz)、F-EMS(400 A,8 Hz)交替搅拌时,Q345E钢Φ600 mm断面碳极差≤0.04%C。

关键词: Q345E钢, ΦD600 mm圆铸坯, 凝固模拟计算, 射钉试验, 宏观碳偏析, 控制