低碳钢连铸板坯表层凝固钩的特征

对不同浇铸条件下的低碳钢连铸板坯进行了凝固钩（Hook）的特征研究，根据凝固钩的形貌概括了凝固钩的不同类型，统计了凝固钩周围气泡和夹杂物的分布，讨论了不同浇铸参数对铸坯凝固钩深度的影响，并通过Bikerman方程和弯月面凝固理论对凝固钩的不同特征进行了解释.结果表明：按形貌可将凝固钩分为完整叶状、双凝固钩、弯曲截断型和二次凝固型四种类型，其中二次凝固型的凝固钩出现的概率最高为46.8%，而完整叶状、弯曲截断型和二次凝固型的凝固钩出现概率分别为25.3%、7.6%和6.3%；研究发现，凝固钩周围的夹杂物数量明显多于其他区域的夹杂物数量，说明凝固钩能够捕获结晶器内上浮的夹杂物；对比不同浇铸参数发现，采用结晶器电磁制动装置（FC-Mold）、减小结晶器水口浸入深度、增大浇铸拉速均能够减小凝固钩的深度；Bikerman方程的计算结果和弯月面凝固理论能在机理上解释凝固钩的形貌特征.

Subsurface hooks in continuous casting slabs of low-carbon steel

Hook characteristics in continuous casting slabs of low-carbon steel under different casting conditions were investigated. According to hook morphology, hooks were classified into different types. Distributions of bubbles and inclusions near hooks were analyzed, and the influence of casting parameters on hook depth was discussed. Bikerman's equations and theory of meniscus solidification were used to explain the various hook morphology. Results show that on the basis of morphology hooks can be classified into four types, including whole-leaf type, double-hook type, truncated type and re-solidified type. The percentage of re-solidified type is the highest (46.8%), and the percentages of whole-leaf type, truncated type and double-hook type are respectively 25.3%, 7.6% and 6.3%. Studies demonstrate that the inclusion number near hooks is obviously higher than that in other zone, indicating floating inclusions in the mold can be captured by hooks. Comparing different casting parameters, the use of FC-Mold, the decrease of the submerged depth of the submerged entry nozzle (SEN) and the increase of casting speed can reduce the hook depth. Calculated results of Bikerman's equation and theory of meniscus solidification can explain the formation mechanisms of different hook morphologies.