2003 Volume 89 Issue 6 Pages 645-652
The surface defects such as a blister and a sliver occur easily on the surface of the ultra low carbon steel sheet. The cause of these defects is bubbles or nonmetallic inclusions entrapped by the fingernail formed by the point's of solidified shell being bent or by the ruggedness part of the solidified shell in the meniscus neighborhood caused by nonuniform growth of solidified shell when molten steel is continuously cast. In this research, the influence of the molten steel flow on the nonuniformity of the solidified shell and on the formation of the fingernail structure in the ultra low carbon steel was examined. The minimum value of the thickness of initially solidified shell increases and nonuniformity decreases by the molten steel flow though nonuniformity of the solidified shell is extremely large in the ultra low carbon steel. Moreover, the size of the fingernail structure decreases as the molten steel flow velocity increases and as the molten steel temperature rises though a big fingernail structure generates in the ultra low carbon steel. In addition, the decrease in the depth of the fingernail structure and in the number of nonmetallic inclusions in continuously cast slabs by the flow which had been given to molten steel in the mold by in-mold electromagnetic stirring were confirmed.
