Quantifying the composite microhardness and fracture toughness of iron ore sinter – a phase-based approach

Microindentation testing was undertaken on sinter phases in iron ore sinter to determine the range and mean of phase/morphology microhardness. The mean fracture toughness of each sinter phase/texture was calculated from indent-associated radial cracks. A value for the composite microhardness (CH) and composite fracture toughness (CFT) was calculated for each sinter sample, based upon the modal proportion of constituent sinter phases. The CH and CFT of sinter phases and each sinter sample was compared to a range of metallurgical indices and major element chemistry to determine the extent of any correlation. Moderate to strong negative correlations were observed between sinter CH and sinter Tumble Index, Reduction Degradation Index and Reducibility Index and between sinter CFT and Tumble Index, Reduction Degradation Index and Reducibility Index. The microindentation technique has the potential to be further developed to routinely characterise and predict the metallurgical performance of sinter.