Mathematical Model Analysis on the Growth of Initially Solidified Shell

Generation Mechanism of Unevenness of Ultra Low Carbon Steel at Initial Stage of Solidification

“…For the mechanism of initial stage of solidification of carbon steel, many studies have been carried out to investigate experimentally and analytically, and it has become clear the generation mechanism of longitudinal surface crack and unevenness of solidified shell growth in what determined the surface quality of steel slabs. Especially, there are many studies [1][2][3][4][5] for the solidification mechanism of low and middle carbon steels, and it has become clear that the surface cracks of steel slabs was caused by peritectic reaction during solidification. It is shown that the surface defects of steel slabs can be reduced by optimizing the cooling conditions in the continuous casting mold from these studies.…”

“…Though, it has been understood that the peritectic reaction caused the unevenness of solidified shell for middle carbon steel, [1][2][3][4][5] it is thought that the unevenness of solidified shell depends on both strength and density as the same as ultra low and low carbon steel. In order to examine the dependency of the rate of change of strength and density as well as the case of ultra low and low carbon steel shown in Fig.…”

“…In the case of the middle carbon steel, the temperature range of peritectic reaction is narrow and the rate of change of high temperature physical properties are large, and at that time the solidified shell becomes non-uniform easily. Though, it was clarified that a non-uniform deformation of the solidified shell for ultra low carbon steel 10) and a longitudinal surface crack on the slab surface for the middle carbon steel 2,5,26) could be decreased by mild cooling, these phenomena are equivalent to the effect of the decreases of the rate of change for high temperature physical precipitates.…”

“…4, the interfacial heat transfer coefficient at the position of Ϫ7ϫ10 Ϫ3 m and ϩ5ϫ10 Ϫ3 m from the center of shell was decreased 40 % lower than the reference value. 5) In this way, it was examined the deformation behavior of solidified shell by the non-uniform cooling. Figure 10 shows the analytical results for temperature and strain of solidified shell at 1.8 s in the case of ultra low, low and middle carbon steel samples.…”

Influence of Carbon Content on Solidifying Shell Growth of Carbon Steels at the Initial Stage of Solidification

“…Mizoguchi et al 5) have analyzed quantitatively shell growth at the initial stage of solidification coupling with the shell deformation due to thermal stress and showed that the unevenness of shell growth is improved by a mild cooling in a mold.…”