低碳钢连铸轻压下工艺的技术研发和应用

Development practice of the soft reduction process in mild steel con-casting

通过建立160 mm×160 mm断面小方坯QD08连铸二维瞬态传热凝固模型,计算了各拉矫辊位置的铸坯温度和铸坯凝固率,研究了不同压下位置和压下量对QD08连铸坯纵剖低倍质量的影响。研究结果表明,对比中心固相率,低碳钢更适宜以凝固率表征轻压下位置并调试压下工艺。铸坯凝固率0.961~1.000压下,铸坯中心质量较好;铸坯凝固率0.986~1.000压下,铸坯中心存在显著的缩孔;铸坯凝固率0.931~0.961压下,铸坯中心出现显著的压下裂纹。拉速较高时,即便在同样的铸坯凝固率位置执行轻压下工艺也更容易产生裂纹。适当降低压下量可明显改善中心裂纹。

By establishing two-dimensional transient heat transfer and solidification model for continuous casting of 160 mm×160 mm square billet QD08,the slab temperature and slab solidification rate at each roll position were calculated,and the effects of reduction and position on the macrostructure quality of billet longitudinal section were studied.The results indicated,compared with the central solid rate,low carbon steel is more suitable for characterizing the soft reduction position and adjusting the reduction process with solidification rate.The billet central quality was best reduced in 0.961-1.000 solidification range.Shrinkage cavity existed in the center of the billet reduced in 0.986-1.000 solidification range.Certer cracks existed when soft reduction was carried out in 0.931-0.961 solidification range.Cracks occuried more eassily at high casting speed under the same reduction proccess.Less reduction quantity significantly decreased the center cracks.