大方坯结晶器内液面波动与卷渣行为

为深入揭示不同水口类型对结晶器内钢液初始流动的影响,以某厂410 mm×530 mm的大方坯结晶器为原型,基于相似原理,采用1:1的物理模型,比较了直通型、五孔和四孔水口浇注时在不同拉速和浸入深度下的结晶器内液面波动和渣层状态。结果表明,3种水口的液面平均波高范围分别为0.20~0.30、0.23~1.10、0.35~1.28 mm。五孔水口和四孔水口的液面波动均比直通水口剧烈,渣层比直通水口活跃,尽管有轻微卷渣但无裸钢现象,这有利于保护渣的熔化和夹杂物的上浮去除。五孔水口和四孔水口对结晶器壁面的冲击比直通水口强,有助于铸坯中心等轴晶率的提高。推荐该大方坯使用多孔水口时浸入深度和拉速分别为170 mm和0.38 m/min,可保证生产顺行和铸坯质量改善。

Liquid level fluctuation and slag entrainment behavior in a bloom mold

To reveal the effect of different nozzle types on the initial flow of molten steel in the mold, a 410 mm × 530 mm billet mold in a certain plant was used as a prototype. Based on the similarity principle, the 1:1 water model has been established to compare the liquid level fluctuation and slag layer state under different casting speeds and immersion depths for the straight-through, five-hole and four-hole nozzle. According to the experimental results, it is found that the average wave height of the three nozzles ranges from 0.20 to 0.30 mm, 0.23 to 1.10 mm and 0.35 to 1.28 mm, respectively. The liquid level fluctuations of the five-hole nozzle and four-hole nozzle are more severe and the slag layers are more active than those of the straight-through nozzle. There is a slight entrapment but the steel is not exposed to the air, which is beneficial to the melting of mold powder and the removal of inclusions. The five-hole nozzle and four-hole nozzle have a stronger impact on the wall of mold than the straight-through nozzle, which is beneficial to the improvement of the central equiaxed crustal ratio. The best of immersion depth and casting speed with the multiple-hole nozzle are 170 mm and 0.38 m/min, respectively, which can ensure the smooth production and the improvement of bloom quality.