Abstract: Based on condition for heavy rail steel concasting at Nol Steelmaking Plant, Wuhan Iron and Steel Co, the math model for solidification heat transfer model of 380 mm x 280 mm bloom has been established, and tested and modified by pin-shooting technique. Simulation results show that the distance of end position of solidification of heavy rail steel U71Mn and U75V from meniscus is respectively 16. 96 ~21. 68 m and 16. 50 ~21. 17 m； with decreasing intensity of secondary cooling or increasing casting speed, the end position of solidification of steel U71Mn and U75V is obviously prolonged forward. According calculated results, as secondary cooling schedule changes from weak cooling (0.346 L/kg) to extra-weak cooling (0.218 L/kg) with casting speed 0. 7 m/min, using soft reduction 5 ~7 mm at Nol -4 stand, the end position of solidification of steel U71Mn and U75V is prolonged to more than 21 m. After concasting process optimization, the qualified percentage for center porosity in bloom of heavy rail steel W rating 1 increases from 89.64% to 99.50% .

Key words: Bloom of Heavy Rail Steel, Numerical Simulation, End Position of Solidification, Soft Reduction, Center Porosity

摘要： 根据武钢第一炼钢厂重轨钢连铸生产条件,建立380 mm ×280 mm方坯凝固传热数学模型,并采用射钉法验证及修正。模拟结果表明,U71Mn和U75V钢的凝固末端各自位于距结晶器液面16.96～21.68 m和16.50～21.17 m;减弱二冷强度或增大拉速,U71Mn和U75V钢凝固终点均会明显后移。根据计算结果,二冷制度由弱冷(0.346 L/kg)改为超弱冷(0.218 L/kg),拉速采用0.7 m/min,应用1～4~#机架轻压下,压下量为5～7 mm,U71Mn和U75V钢凝固终点延长至21 m以上。连铸工艺优化后,重轨钢大方坯中心疏松Ⅰ级内平均合格率由89.64%提高到99.50%。

关键词: 重轨钢铸坯, 数值模拟, 凝固末端, 轻压下, 中心疏松