Compressive Creep Measurements of Fired Magnesia Bricks at Elevated Temperatures Including Creep Law Parameter Identification and Evaluation by Finite Element Analysis

Abstract

Creep behavior is very important for the selection of refractory materials. This paper presents a methodology to measure the compressive creep behavior of fired magnesia materials at elevated temperatures. The measurements were carried out at 1150–1500 °C and under compression loads from 1–8 MPa. Creep strain was calculated from the measured total strain data. The obtained creep deformations of the experimental investigations were subjected to detailed analysis to identify the Norton-Bailey creep law parameters. The modulus of elasticity was determined in advance to simplify the inverse estimation process for finding the Norton-Bailey creep parameters. In the next step; an extended material model including creep was used in a finite element analysis (FEA) and the creep testing procedure was reproduced numerically. Within the investigated temperature and load range; the creep deformations calculated by FEA demonstrated a good agreement with the results of the experimental investigations. Finally; a finite element unit cell model of a quarter brick representing a section of the lining of a ferrochrome (FeCr) electric arc furnace (direct current) was used to assess the thermo-mechanical stresses and strains including creep during a heat-up procedure. The implementation of the creep behavior into the design process led to an improved prediction of strains and stresses.