Abstract: Nail-shooting technique is applied to measure shell thickness of 240 mm x 240 mm bloom of steel 35CrMoA ,20CrMoA, GCrl5 and 60Si2MnA produced by the continuous caster. Length of the liquid core and solidification coefficient are calculated by using the solidification law. The electromagnetic stirring position of F-EMS at different drawing speeds is calculated by the solid phase ratio of 0. 70 and 0. 75 for the 240 mm x 240 mm bloom. The relationship between solidification coefficient of continuous casting machine and each process parameter is analyzed. The process optimization measures are： changing the electric stirring position, and modifying the F-EMS position to install according to high carbon steel GCrl5 and 60Si2MnA, and adjusting the casting speed value of four steel of 35CrMoA, 20CrMoA, GCrl5 and 60Si2MnA to 0. 80, 0. 81, 0. 78 and 0. 80 m/min. The quality of billet is improved greatly after the process improvement, i. e. qualified ratio of center segregation rating ≤0.5 increases from original ≤40% to 100% and that of center porosity rating ≤1.5 increases from original ≤50% to ≥90%.

摘要： 利用射钉法测定了连铸机生产240mm×240mm断面35CrMoA、20CrMoA、GCr15、60Si2MnA四个钢种的铸坯凝固坯壳厚度,并根据凝固定律计算了其液相穴长度和综合凝固系数;针对240mm×240mm方坯选择固相率0.70、0.75进行计算得出F-EMS在不同拉速条件下的电磁搅拌位置,分析了工艺参数对连铸机凝固系数的影响,提出的工艺优化措施为:改变电磁搅拌位置,F-EMS位置修正为根据高碳钢GCr15、60Si2MnA来安装,35CrMoA,20CrMoA,GCr15和60Si2MnA四钢种拉速值分别调整为0.80、0.81、0.78、0.80 m/min。工艺优化后铸坯质量得到明显改善,中心偏析级别≤0.5合格率由原来≤40%提高到100%,中心疏松级别≤1.5合格率由原来≤50%提高到≥90%。

关键词: 射钉法, 240 mm x 240 mm方坯连铸, , 末端电磁搅拌, , 综合凝固系数