On the Behavior of Al2O3 Clusters during the Solidification of Continuously Cast Slabs

In the slabs of Al-Si killed steel cast continuously by the vertical-type caster, some Al2O3 clusters accumulate below the slab surface. By investigation on the macro-and micro-structures of slabs, it was clarified that the Al2O3 clusters were entrapped when the columnar dendrite grew discontinuously. This discontinuity has been improved by the control of the casting temperature. Then, the defect originated from the non-metallic inclusions at welds of ERW pipe, especially that with large thickness and small diameter, has been reduced.