Effects of carbon content and grain orientation on the crack growth behaviour in magnesia-carbon refractory bricks

Abstract

Effects of carbon content and loading direction/grain orientation on the crack growth resistance of MgO-C refractories were examined via evaluating R-curve, critical stress intensity factor and bridging stress derived from the results of three point bending testing on single edged notched beam samples. The results indicated that crack growth resistance, critical stress intensity factor and bridging stress all increased with increasing the carbon content in the refractories, and were greater in the loading direction horizontal to than perpendicular to the sample pressing direction. Nevertheless, the stress intensity factor at crack initiation was similar in all cases of samples containing different levels of carbon. Based on these, it can be concluded that an MgO-C refractory with a higher carbon content would have better resistance against crack propagation after initiation, but would not show obvious improvement in its resistance against crack initiation.