Alloy design for heat and abrasion resistant high alloy cast iron

Influences of Mo, Nb, V on the microstructure, the oxidization behavior and the high-temperature compressive strength of 35-40%Cr-9%Ni cast irons were investigated. The addition of Mo raises the compressive strength at higher temperature, since Mo distributes into the matrix and enhances the high temperature strength. The crystallization of fine eutectic M7C3 and M2C type carbides should also contribute to the higher strength. The MC type carbide formers such as V and Nb can significantly improve the abrasion resistance at lower temperature. However, these elements also promote the oxidization of alloys. Especially V causes abnormally severe in both matrix and the hard phases. On the other hand, Nb preferentially distributes to NbC, the oxidation behaviors of M7C3 and matrix are little influenced by the addition of Nb. Among the trial alloys, Fe-2.2 4.5%C-35 40%Cr-9%Ni-5%Mo-0/7%Nb maintain 900Mpa of compressive strength even at 1073K, while the strength of conventional heat resistant alloys and high Cr cast irons drop below 500MPa at the temperature from 873K to 923K. The developed alloys show high oxidation resistance and superior high temperature wear resistance. (C) 2003 Maney Publishing.