Optimizing heat treatment and wear resistance of high chromium cast irons using computational thermodynamics

Computational thermodynamics was applied to analyze seven high chromium cast iron compositions in order to optimize their hardness and wear resistance after quench and tempering heat treatments. Five of these materials were candidate alloys to be applied in blast furnace wear rings and two were developed for grinding balls. The methodology consisted of establishing the phase formation sequence of each alloy, calculating the composition of the austenite and the corresponding martensite start temperature (Ms) and selecting the appropriate heat treatment temperature, with the best compromise between martensite C content for hardness, Cr content for corrosion resistance and Ms temperature to avoid excessive retained austenite. Rubber wheel tests and pilot plant ball mill were used to evaluate the performance of the best combinations of chemical composition and heat treatment. The selected alloys and heat treatments were approved for use in the respective industrial applications.