Metal dusting of nickel-base alloys

Nickel-base alloys are generally less susceptible to metal dusting than steels and the attack is slower. Exposures in strongly carburizing CO-H2-H2O mixtures at 650°C and 750°C have shown, however, gradually increasing attack on the alloys with lower Cr-content. Alloy 600 and even 601 were gradually attacked by pitting, whereas for alloys with >25 % Cr the materials loss was negligible even after 10,000 h. For these alloys such as 602 CA and 690 the formation of a protective chromia scale is strongly favored compared to carbon ingress and metal dusting.