Abstract: The production flow sheet for heavy bloom of steel Q345E (/% : 0.14-0.17C, 0.20-0.30Si, 1.28-1.38Mn, ≤0.011P, ≤0.005S, 0.015-0.030A1, 0.032-0.045V) is 65 t LD-LF-VD-Φ600 mm round bloom CC process. With the measures including using sliding plate to stop slag in tapping , and adding pre-melted synthetic slag (/% : 40-50CaO, ≤9SiO₂,30-40Al₂O₃, 3-7MgO, 8-10A1), steel-clad aluminium, deoxidizer and alloys, controlling casting speed 0.22 m/min, overheating extent of liquid (25 ± 5)℃ and constant liquid level 900 mm in 32 t tundish, whole process shield casting and electromagnetic stirring, the Φ600 mm casting round bloom of steel Q345E for flange is pilot-produced. The production results show that there is no visible surface defect such as scab and bulging, the rating of center line shrinkage is 0.5, the center porosity 1.0 and the carbon segregation ≤1.09, and the impact energy of steel at -50 ℃ is more than 100 J, all meet the requirement.

Key words: HSLA Steel Q345E, 65 t LD-LF-VD-CC Flow Sheet, Φ600 mm Cast Round Bioom, Steel for Flange, Production Practice

摘要： Q345E钢(/%:0.14~0.17C、0.20~0.30Si、1.28~1.38Mn、≤0.011P、≤0.005S、0.015~0.030Al、0.032~0.045V)大圆坯的生产流程为65 t LD-LF-VD-Φ600 mm圆坯CC工艺。通过出钢时滑板挡渣,加入预熔合成渣(/%:40~50CaO、≤9SiO₂、30~40Al₂O₃~7MgO、8~10Al)、钢芯铝、脱氧剂和合金,控制拉速0.22 m/min,32 t中间包钢水过热度(25±5)℃,恒液面900 mm,全程保护浇铸和电磁搅拌等措施,试生产法兰用Q345E钢Φ600mm连铸圆坯。生产结果表明,铸坯表面无可见冷疤、鼓肚等缺陷,中心缩孔0.5级,中心疏松1.0级,碳偏析≤1.09,-50℃低温冲击功超过100 J,完全满足标准要求。

关键词: Q345E低合金高强度钢, 65 t LD-LF-VD-CC流程, Φ600 mm连铸圆坯, 法兰用钢, 生产实践