Nonlinear Finite Element Analysis on Monolithic Refractory Lining Material (Part 3 Creep-Behavior of Alumina-Magnesia Monolithic Refractory Lining Material)

摘要

In design analysis of refractory materials, it is necessary for the analyst to establish an appropriate methodology for prediction, upon knowing thoroughly the behavior due to the material inhomogeneity and pertinent nonlinearities. The alumina-magnesia compound, in which the reaction may occur during the service period, would resume a complicated material behavior with thermo-reactive expansion, elastoplasticity, and creep.In this report, the creep material coefficients associated with the Norton-Baily relation were determined during the creep test in an axial compression at various temperatures. The obtained material coefficients were used in a creep analysis of the ladle lining material subjected to a cyclic thermal shock simulating its operating conditions. The finite element analysis accounts for the effects of the spinel reaction occurring in the material during the heat cycle history, as well as for the creep effects. The spinel reaction expansion enhanced the compressive stress in the surface area of the lining in the heat-charge cycles of the analysis. The compressed stress is subsequently relaxed by the emerged creep strain. There exists a thin layer where the stress cascades at about 40 to 70mm from the surface in the cycles. Under the thermal-cycle loading situations, the repeated stress trip would accumulate possible micro defects, such as micro-cracking or damage, which may eventually be promoted to the delamination occurring on the surface of the ladle.The analytical results show the reliability of the developed procedure in reference to the experimental evidences found in relevance to the delamination that occurs on the surface layer of the material.