Journal article
Behaviour of Z phase in 9–12%Cr steels
The literature on the behaviour of modified Z phase Cr(V,Nb)N in creep resistant martensitic 9–12%Cr steels is briefly reviewed. Ten different 9–12%Cr steels were investigated after prolonged exposure at 600–660uC; the modified Z phase was found in all of them. In steels with high Cr content (11–12%), Z phase precipitates much faster than in 9%Cr steels.
Precipitation of Z phase is associated with dissolution of MX carbonitrides, and causes a breakdown in long term creep strength in 9–12%Cr steels. High Cr steels show creep instabilities accompanied with Z phase precipitation, whereas low Cr steels show good long term creep stability. A niobium free CrVN variant of the modified Z phase was observed for the first time during the course of this work.
The solution temperature of the Cr(V,Nb)N and CrVN modified Z phases was found to be close to 800uC for 11–12%Cr steels, much lower than the 1200–1250uC solution temperature of the unmodified CrNbN Z phase. Above the solution temperature the modified Z phase is replaced by MX particles.
Language: | English |
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Year: | 2006 |
Pages: | 49-57 |
ISSN: | 17489245 and 17489237 |
Types: | Journal article |
DOI: | 10.1179/174892306X99732 |
ORCIDs: | Danielsen, Hilmar Kjartansson and Hald, John |