Laves-phase evolution during aging in 9Cr-1.8W-0.5Mo-VNb steel for USC power plants

Xue Wang, Qiang Xu, Shu Min Yu, Lei Hu, Hong Liu, Yao Yao Ren

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

Long term precipitation and coarsening of Laves-phase in tungsten strengthened 9% Cr steel under thermal aging at 923 K was investigated and reported in this paper. It experimentally measured the evolution of mean particle size, the number density, the volume fraction of Laves-phase precipitates, the partition coefficients of W and Mo in the matrix, as well as the change of hardness. Its main conclusions were: 1) Laves-phase nucleates and grows rapidly on grain boundaries and lath boundaries within the first 1500 h of aging time; 2) The two stages characteristics and kinetics of Laves-phase nucleation and growth which were determined experimentally; 3) The coarsening of Laves-phase is much faster than that of M23C6 carbides; 4) The precipitation of Laves-phase produces a pronounced matrix depletion of W and Mo atoms; and 5) The precipitated Laves-phase gives rise to weaker precipitation strengthening in comparison with M23C6 carbides, and causes the loss of hardness due to the depletion of Mo and W from the solid solution. This paper contributes to the knowledge of kinetics of Laves-phase precipitation and coarsening, providing the essential information for comparative investigation of creep damage mechanisms. This paper also contributes to the understanding the creep damage broadly.

Original languageEnglish
Pages (from-to)219-228
Number of pages10
JournalMaterials Chemistry and Physics
Volume163
DOIs
Publication statusPublished - 1 Aug 2015

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