A creep model with different properties under tension and compression — Applications to refractory materials

Abstract

Refractories are materials designed to work at high temperatures, and are applied in steel making, cement making, aerospace engineering, and other fields where a combination of chemical and mechanical stability is paramount. Due to such high temperature applications, creep strains play an important role in the mechanical performance of refractories, that often present an asymmetric behavior, i.e., different creep strain rates under tension and compression. The aim of this work is to propose an asymmetric creep model that can be used to simulate the time-dependent non-linear primary and secondary creep behavior of refractories at high temperature. The proposed model uses a split of the stress tensor into positive and negative parts and further calculation of the contribution of each stress sign to the overall strain rate using a weighted average over the equivalent stresses. An experimental procedure is proposed in order to identify the tensile and compressive parameters of an alumina-spinel refractory used in steel ladle linings, using a Brazilian test and a subset-based Digital Image Correlation (DIC) technique, for a temperature of 1300 °C.