Abstract
In the continuous casting of steel, unsteady bulging contribute to degradation of the slab quality. It has been reported that unsteady bulging is promoted by uneven solidified in the mold, but the effect of uneven solidified on unsteady bulging had not been clarified. In this study, a FEM (finite element model) simulation was constructed. Shell deformation was calculated by an elasto-plastic analysis assuming that the slab moves between the rolls, considering time dependency. The bulging value and mold level fluctuation, which change corresponding to the solidified shell thickness, ferrostatic pressure and roll pitch, were obtained.
In the simulation results, the shell is deformed by ferrostatic pressure. The bulging shell pushes out under the rolls in the thickness direction, and unsteady bulging causes. While the shell is passing through the same pitch rolls, unsteady bulging becomes larger. When the solidified shell is uneven, stress concentrates on the thinner portions. The stress concentration accelerated the unsteady bulging even at the same average shell thickness. Based on this result, an operational index for suppressing unsteady bulging by reducing unevenness of the solidified shell is proposed.
