ABSTRACT9-12wt%Cr steels for high temperature applications in fossil fired power plants rely upon precipitate strengthening from (V,Nb)N MX nitrides for long term creep strength. During prolonged exposure at service temperature another nitride precipitates: Cr(V,Nb)N Z-phase. The Z-phase slowly replaces MX, eventually causing a breakdown in creep strength. This paper reviews the Z-phase and its behaviour in 9-12wt%Cr steels including thermodynamic modelling, crystal structure, nucleation process and precipitation rate as a function of chemical composition. The influence of Z-phase precipitation upon long-term creep strength is assessed from several different 9-12wt%Cr steel grades and alloy design philosophies.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.