Computational analysis of the effect of taper design of continuous casting molds on solidifying steel shells

Abstract

The growth and the deformation of the solidifying steel shell in the continuous casting process were calculated considering the taper of the mold's narrow face. The mechanism of uneven shell growth in the mold was discussed by using computational method and observations of the shell at various operating conditions such as taper and slab width. It was found that the shell at the bottom of the mold becomes uneven when the narrow face taper is insufficient. The increase of taper is effective to even shell growth， but excessive taper causes wear of mold's copper plate and breakout of the shell. To solve these problems， various kinds of mold taper design such as multiple and parabolic have been developed and adopted to molds' narrow faces. At the actual operation of continuous casting， many kinds of steel grades are cast in various casting speed and width at the same mold. So， the online change of the tilt of the narrow face is done according to the operating condition. When applying multiple taper design to this width changing type mold for slab， the problem is that the rate of upper or lower taper changes in different slab width. In this paper， the relationship between multiple taper and the uniformity of the shell growth was discussed considering slab width quantitatively by using computational model and observed shell thickness of slab. By using the developed calculation models, the multiple taper designs were optimized and applied to the actual continuous casting molds' narrow faces.

Influence of heat flux different between wide and narrow face in continuous casting mould on unevenness of hypo-peritectic steel solidification at off-corner

“…The slab thickness and width were 250 and 2100 mm, respectively. After the casting experiment, slab samples were cut, and and were evaluated by measuring the white band [34] on the cut surface revealed by etching with picric acid. The white band can be formed at the solidified shell-liquid interface continuously at off-corner in the cross section perpendicular to the casting direction due to the discharge flow from the submerged entry nozzle and reverse flow on the narrow side mould.…”