The Mechanism of Unsteady Bulging and Its Analysis with the Finite Element Method for Continuously Cast Steel.

Abstract

The movements of the driven rolls were measured during the continuous casting of steel and their fluctuations were compared with other signals such as the casting speed and the mold level. From the observation of large fluctuations in the movements of the driven rolls and the unevenness in the thickness of the solid shell, it is proposed that the unevenness in the thickness of the solid shell is the main reason for unsteady bulging during the casting of medium carbon steel. A two-dimensional model over the successive rolls was used to calculate the bulging profile and its changes with time, during the fluctuations in the casting speed, with the finite element method. As a result, the calculations were in good agreement with the experimental results, and, it could be concluded that the period of unsteady bulging is greatly influenced by the roll pitch, therefore, depends on the locations where different roll pitches occur, and is somewhat affected by casting speed variations. Finally, based on the calculations and the experimental results, the effect of the unsteady bulging on the mold level was discussed.