Improvement of the Initial Stage of Solidification by Using Mild Cooling Mold Powder.

Abstract

The initial stage of solidification for continuous casting is very important in optimising the surface quality of steel. It is well known that hypo-peritectic steel has problems with longitudinal cracking due to shrinkage resulting from the δ→γ transformation. High speed continuous casting, with a speed range of 4-5 m/min, suffers from the same problem. For a round-shaped billet caster, the shape of the mold cross section is at a disadvantage with regard to longitudinal cracking. In this study, mild cooling mold powders were developed in order to improve the surface quality of high speed casting slabs and round-billets. The results can be summarized as follows; 1) High CaO/SiO2 ratio mold powder with a high solidification temperature is most suitable for a slab caster. 2) Low CaO/SiO2 ratio mold powder with a high solidification temperature is most suitable for a round billet caster. 3) The effect of radiation in liquid powder film is bigger than solid powder film.