THERMAL-STRESS ANALYSIS OF FUSED-CAST AZS REFRACTORIES DURING PRODUCTION .2. DEVELOPMENT OF THERMOELASTIC STRESS MODEL

Mathematical models of heat flow and thermo-elastic stress, based on the finite-element method, have been developed and utilized to analyze the ''voidless,'' fused-cast, AZS, solidification process. The results of the mathematical analysis, in conjunction with information obtained in a comprehensive industrial study, presented in Part I of this paper, describe the mechanisms for the formation of the various crack types found in the fused-cast product. Thermal stresses are generated early in the solidification process by rapid cooling of the refractory surface as it contacts the initially cool mold and later in conjunction with the tetragonal-to-monoclinic phase transformation which occurs in the zirconia component of the AZS refractory. Applying this model, castings were made using a revised mold design. Preliminary results indicate these castings to be free of objectionable transverse cracks.