Laves-phase precipitates in a low-carbon 9% Cr martensitic steel during aging and creep at 923K

The precipitation of the Laves-phase in a low-carbon 9% Cr heat resistant steel was studied under conditions of aging and creep at 923K. The Laves-phase of Fe2(W,Mo)-type with a ratio of Mo:W of 1:5 was observed on various boundaries in a tempered martensite structure after a long period of aging/cr...

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Bibliographic Details
Published in:Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2014-10, Vol.615, p.153-163
Main Authors: Fedorova, I., Belyakov, A., Kozlov, P., Skorobogatykh, V., Shenkova, I., Kaibyshev, R.
Format: Article
Language:English
Subjects:
Chromium
Coarsening
Creep (materials)
Creep tests
Dislocations
Electron microscopy
Fracture mechanics
Martensite
Precipitation
Steel
Tempered martensite
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Summary:The precipitation of the Laves-phase in a low-carbon 9% Cr heat resistant steel was studied under conditions of aging and creep at 923K. The Laves-phase of Fe2(W,Mo)-type with a ratio of Mo:W of 1:5 was observed on various boundaries in a tempered martensite structure after a long period of aging/creep. The Laves-phase precipitations provided effective stabilization of the tempered martensite lath structure and therefore promoted creep resistance, although their effect on the dislocation substructure was negligibly small. The mean size of the Laves-phase particles (D) gradually increased with aging/creep time (τ) and could be expressed as D4−D04=Kτ, were K=5×10−34m4/s for aging and K=13×10−34m4/s for creep. The large Laves-phase particles, which coarsened during the creep tests, served as preferential sites for pore and crack nucleation leading to fracture.
ISSN:0921-5093
1873-4936
DOI:10.1016/j.msea.2014.07.046