结晶器电磁搅拌对重轨钢大方坯内部质量的影响

Effect of mould electromagnetic stirring on innter quality of heavy rail steel bloom

采用对比试验研究的方法分析不同电磁搅拌强度下对重轨钢大方坯内部质量的影响,试验中采用搅拌电流分别为250、350、400、450和500A,浇铸的铸坯均为24块。研究结果表明:搅拌电流由250A增至500A,铸坯中心偏析、中心疏松等的评判级别≤1.0级的比例分别达到95.83%和87.50%,研究确定的重轨钢连铸电磁搅拌强度I=500A是改善重轨钢连铸坯内部质量的一项关键技术。使用结晶器电磁搅拌后,在电磁力的作用下,凝固前沿的液相对流会加剧,对以柱状晶生长的凝固前沿进行冲刷和清洗,凝固前沿的液相流动使母液与两相区的液体互相混合,使溶质浓度趋向均匀。

The present paper analyzes the effect of different electromagnetic stirring intensities on the inner quality of the heavy rail steel bloom through comparison of the results out of different experiments. In the experiments 24 blocks of concasting bloom are used as the testing pieces and the stirring currents adopted are 250, 350,400, 450 and 500 A respectively. Results show that proportions of judging grade≤l. 0 on the central segregation and central porosity of the bloom account to 95.83 %and 87. 50 %, and the 50/3 A current of electromagnetic stirring intensity determined in the research is a key technological parameter for improvement in the inner quality of heavy rail steel. Liquid phase convection at the solidifying front can be intensified due to the action of the electromagnetic force after implermentation of the mould electromagnetic stirring and at this time the intensified convection may further scour and rinse solidification front, and as the results the liquid flow at the solidification front inevitably leads to a mixture of the matrix with the liquid of the dual-phase and thus the concentration of the solute tends to be more homogeneous.