Stress intensity factor and fatigue crack propagation assessment of mode-I failure in alumina-calcium hexaluminate refractories

Alumina-calcium hexaluminate refractories experience crack development under severe conditions, leading to a significant reduction in mechanical strength. The external finite element method and Paris' law were employed to investigate the effects of external load and in-situ crack length on stress intensity factor. Fatigue life and crack propagation process of refractories were simulated for varying CAx contents under Model I failure. The findings revealed a linear correlation between the stress intensity factor and external load for a fixed in-situ crack length (a <= 16 mm). The ultimate strength of alumina-calcium hexaluminate refractories is inversely proportional to the in-situ crack length. The material's microstructure significantly influences the ultimate strength of refractories, whereas the crack propagation ratio at the interface-to-the aggregate level strongly affects fatigue life. Refractories with a CAx content of 29.78% exhibit the longest fatigue life, attributed to the favorable formation of CA6/CA2 and the highest interface-to-aggregate crack propagation ratio.