The removal of superheat from continuous casting molds

Abstract

The superheat contained in liquid steel must be removed before it can solidify. This heat represents a significant fraction of the total heat removed by the mold. Its dissipation has a great influence on growth of the solidifying shell and later on development of the microstructure. To investigate this, a finite-element model has been applied to compute the fluid flow and temperature distribution within the liquid pool and heat transfer to the inside of the solidifying shell of a continuously-cast steel slab. It includes separate models of the nozzle and mold cavity using the K-ε turbulence model in FIDAP. Calculated velocities have been compared with experiments using a plexiglass water model. Heat transfer predictions are compared with available liquid temperature measurements. Results indicate that the maximum in heat input to the shell occurs in the vicinity of the impingement point on narrow face, and confirms that most superheat is dissipated in or just below the mold. The model is then used to predict the effect of casting variables, superheat temperature difference, casting speed, nozzle jet angle, mold width, and submergence depth on flow pattern and heat flux to the narrow face shell. Superheat temperature difference and casting speed have the most important effects on heat flux. Calculated heat flux profiles are then input to a 1D solidification model to show their effect on growth of the narrow face shell.