Stress and Strain Evolution in Cast Refractory Blocks during Cooling

Abstract

A computational model has been developed to study the stress and strain histories experienced by zirconia-containing cast refractory blocks when they are cooled from the casting temperature. Incorporated into the model are strong temperature dependencies of the following material properties: elastic modulus, flow strength, thermal conductivity, and thermal expansion. The pressure-sensitive Drucker-Prager plasticity model has been used to account for the substantial difference between the tensile and compressive stress-strain behaviors found in these refractories. The temperature-induced phase transformation in the zirconia, as well as the overall thermal contraction, are united by introducing a coefficient of total dilatation. A nonuniform radial distribution of the transforming phase is also incorporated. The parameters that control the time-dependent stress and strain responses are identified by performing calculations that span the range of expected variables. Process strategies for manufacturing crack-free blocks are suggested.