THE EFFECT OF CRYSTALLIZATION OF MOLD POW DER ON THE HEAT-TRANSFER INCONTINUOUS-CASTING MOLD

It has been known that one of the primary trouble on the production of middle carbon grade steel is longitudinal cracks on the cast surface, and occurrence frequency of these cracks is effectively I educed with a lower heat flux in a mold. In order to decrease the heat flux in th e mold, a mold powder with high crystallization temperature has been o rdinarily used. To make clear the mechanism of lowering heat flux in t he mold using the mold powder, laboratory experiments were conducted. Thermal resistance was measured using a dipping test of copper mold, w hich had several thermocouples on the surface. Interfacial thermal res istance was about 2-3 times of thermal resistance of film. To clarify the change of the surface texture by crystallization, the surface of p owder plate was observed with a laser microscope. The surface started to wave, when the glass changed to crystal above 830K. Therefore, it i s supposed that the wave on the surface of of the powder film caused a n increase in the interfacial thermal resistance.