低碳钢Q345E Φ600mm连铸圆坯宏观碳偏析的控制
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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L_1-38、L_2-6和L_3-5 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。
The metallurgical flow sheet of steel Q345E(/%:0.13~0.17 C,0.24~0.28 Si,1.02~1.40 Mn,0.015~0.040 Al,≤0.015 P,≤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 and0.22 m/min and combined with pin-shooting test in conditions of casting speed 0.22 m/min,liquid overheating extent 20℃,mold cooling rate 4 600 L/min(water temperature difference between inlet and outlet 2.7℃),secondary cooling water rate L_1-38,L_2-6 and L_3-5 L/min,the position of end of liquid core-distance from meniscus 22.4 m for Φ600 mm round bloom of steel Q345 E 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 speed0.22~0.24 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 Q345 E at cross section of Φ600 mm round bloom is below 0.04%C.
The metallurgical flow sheet of steel Q345E(/%:0.13~0.17 C,0.24~0.28 Si,1.02~1.40 Mn,0.015~0.040 Al,≤0.015 P,≤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 and0.22 m/min and combined with pin-shooting test in conditions of casting speed 0.22 m/min,liquid overheating extent 20℃,mold cooling rate 4 600 L/min(water temperature difference between inlet and outlet 2.7℃),secondary cooling water rate L_1-38,L_2-6 and L_3-5 L/min,the position of end of liquid core-distance from meniscus 22.4 m for Φ600 mm round bloom of steel Q345 E 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 speed0.22~0.24 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 Q345 E at cross section of Φ600 mm round bloom is below 0.04%C.
引文
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[3]许伟阳,曹志刚,颜慧成,等.齿轮钢大方坯宏观碳偏析及形成机制[J].炼钢,2011,27(1):63-67.
[4]祝宜明,张文基,巨清高.轴承钢连铸中心碳偏析的探讨[J].连铸,2001(1):34-36.
[5]Bridge M R,Rogers C D.Structural Effects and Band Segregate Formation during Electromagnetic Stiring of Strand-Cast Steel[J],Metallurgical Transactions B,1984,15B(9):581-585.