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根据武汉钢铁集团鄂城钢铁有限责任公司Q345钢宽板坯实际生产条件,建立宽板坯凝固传热数学模型来确定其凝固末端位置,并采用射钉法验证及修正。结果表明:射钉试验测量结果与凝固传热数学模型结果误差在±1.3%以内,模型计算结果能真实反映此钢种宽板坯凝固末端位置。在典型拉速1.15 m/min下,200 mm厚宽板坯两相区位于距结晶器液面13.32～20.95 m处;在典型拉速0.95 m/min下,250 mm厚宽板坯两相区位于距结晶器液面16.16～23.45 m处;在典型拉速0.80 m/min下,300 mm厚宽板坯两相区位于距结晶器液面19.34～27.65 m处。不同拉速及铸坯厚度下,凝固末端位置差别较大。采用优化的轻压下技术后,Q345宽板坯中心偏析Ⅰ级内平均合格率由85.4%提高到99.5%。
According to the actual production conditions of Q345 steel wide slab of Wuhan Iron and Steel Group Echeng Iron & Steel Co., Ltd., a mathematical model of solidification and heat transfer of wide slab was established to determine the position of its solidification tip and verified by the nailing method. The results show that the error between the measurement results of the nailing test and the mathematical model of the solidification heat transfer is within ± 1.3%. The calculation results of the model can truly reflect the position of the end of solidification of the wide slab. Under the typical pulling speed of 1.15 m / min, the two-phase zone of 200 mm thick slab is located at 13.32 ~ 20.95 m away from the liquid level of the mold. At a typical casting speed of 0.95 m / min, the 250 mm thick slab two- Located 16.16 ~ 23.45 m away from the liquid level of the mold. At a typical drawing speed of 0.80 m / min, the two-phase zone of 300 mm thick slab is located at a distance of 19.34-27.65 m from the mold surface. Different casting speed and slab thickness, the coagulation end position difference is larger. With the optimized soft reduction technology, the average pass rate of Q345 wide slab center segregation class I increased from 85.4% to 99.5%.