40Cr合金结构钢方坯连铸二冷制度的优化

Optimization of secondary cooling scheme for 40Cr alloy structural steel in billet continuous casting

建立了连铸方坯的凝固传热模型,并采用红外测温法对模型的准确性进行了验证。通过模型计算分析了40 Cr合金结构钢现行二冷制度存在的问题,发现足辊段冷却强度过大,二冷段一区存在较大的温度回升;二冷比水量偏高,铸坯在矫直点的表面温度偏低。将不同的水量调整参数(K值)组合代入模型计算,优化得到了较为合理的K值组合K0=0.3,K1=1.0,K2=0.9,K3=0.7。优化K值后,降低了足辊段水量,二冷段一区的温度回升幅度变小;同时降低了二冷比水量,提高了铸坯的矫直温度,避开了脆性温度区,降低了铸坯裂纹的发生率,为现场连铸工艺的优化提供了技术指导。

The solidification and heat transfer model for billet continuous casting is es- tablished and the model accuracy validated by the infrared temperature measurement method. By model calculation the problems currently existing in the secondary cooling schedule for the 40 Cr alloy steel is analyzed and at the same time the problems of over strong cooling intensity at the food roll segment, higher temperature recovery existing in the No. 1 zone of the secondary cooling segment, excessive secondary cooling water volume and relatively lower surface temperature of the billet at the straightening zone are found out. A reasonable set of K-value combination （ water volume adjustment pa- rameters） is fed into the model computer after optimization and then a more reasonable K value combination namely K0 = 0. 3, K1 = 1.0, K2 = 0. 9, K3 = 0. 7 is obtained. At the same time the secondary cooling water rate is lowered, the straightening temperature of the billet raised, the brittle temperature zone avoided and thus the rate of crack occur-rence of the billet reduced. It can be used as guidance for the process optimization of the billet continuous casting.