Journal ArticleDOI
Stabilization of martensitic microstructure in advanced 9Cr steel during creep at high temperature
TLDR
In this paper, the stabilization of martensitic microstructure in the vicinity of prior austenite grain boundaries during creep has been investigated by the addition of boron and by a dispersion of nano-size MX nitrides.Abstract:
In order to improve the long-term creep strength of 9%Cr steel, the stabilization of martensitic microstructure in the vicinity of prior austenite grain boundaries during creep has been investigated by the addition of boron and by a dispersion of nano-size MX nitrides. Creep tests were carried out at 923 K for up to about 3×10 4 h. Boron is enriched in the M 23 C 6 carbides during aging and creep, especially in the vicinity of prior austenite grain boundaries. This reduces the coarsening rate of M 23 C 6 carbides, which effectively stabilizes the martensitic microstructure in the vicinity of prior austenite grain boundaries. A dispersion of nano-sized MX nitrides but no M 23 C 6 along boundaries also gives rise to excellent pinning force for migrating boundaries during creep, as shown by approximately two orders of magnitude longer time to rupture than ASME-P92. The stabilization of martensitic microstructure retards the onset of tertiary or acceleration creep, which results in lower minimum creep rate and longer time to rupture.read more
Citations
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Precipitate design for creep strengthening of 9% Cr tempered martensitic steel for ultra-supercritical power plants
TL;DR: The suppression of particle coarsening during creep and the maintenance of a homogeneous distribution of M23C6 carbides near prior austenite grain boundaries are effective for preventing the long-term degradation of creep strength and for improving long- term creep strength by the addition of boron.
Journal ArticleDOI
Development of next generation tempered and ODS reduced activation ferritic/martensitic steels for fusion energy applications
Steven J. Zinkle,Steven J. Zinkle,J.-L. Boutard,David T. Hoelzer,Akihiko Kimura,Rainer Lindau,G.R. Odette,Michael Rieth,Lizhen Tan,Hiroyasu Tanigawa +9 more
Journal ArticleDOI
Bainitic and martensitic creep-resistant steels
TL;DR: A number of new alloy-design concepts based on microstructure stabilization have been proposed for the development of highly creep-resistant bainitic 3Cr and martensitic 9-12Cr steels with higher creep rupture strength than existing high strength steels such as T23 and P92 as mentioned in this paper.
Journal ArticleDOI
Analysis of the hysteresis loops of a martensitic steel: Part I: Study of the influence of strain amplitude and temperature under pure fatigue loadings using an enhanced stress partitioning method
TL;DR: In this article, a study of the cyclic stress partitioning is presented, where the authors identify the microstructural mechanisms leading to the softening effect usually presented by martensitic steels under cyclic loadings.
Journal ArticleDOI
9%Cr heat resistant steels: Alloy design, microstructure evolution and creep response at 650 °C
TL;DR: In this paper, two sets of alloys were produced: 9%Cr alloys with 0.1%C and 0.05%C (always wt) and 9%cr alloys containing ∼0.03% Ti with 0 1%C/0.5%C.
References
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Journal ArticleDOI
JCPDS-International Centre for Diffraction Data
Camden R. Hubbard,G.J. McCarthy +1 more
Journal ArticleDOI
Improved Utilization of Added B in 9Cr Heat-Resistant Steels Containing W
TL;DR: In this article, the effect of improved heat treatment on creep strength and distribution of B in precipitates is investigated to effectively utilize and decrease added B. The authors have revealed in the previous report that the addition of 139ppm B significantly improves creep strength of the steels, whereas most of added B forms unidentified borides, which are deemed almost ineffective to creep strength.
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The role of microstructural instability on creep behavior of a martensitic 9Cr-2W steel
TL;DR: In this paper, the microstructural instability during creep and its effect on creep behavior were investigated for a martensitic 9Cr-2W steel, which was developed as a low radioactive steel suitable for fusion reactor structure.
Journal ArticleDOI
Effect of quenching, tempering, and cold rolling on creep deformation behavior of a tempered martensitic 9Cr-1W steel
TL;DR: In this paper, the effect of quenching, tempering, cold-rolling, and aging treatments on the creep-deformation behavior was investigated for a tempered martensitic 9Cr-1W steel at 873 K, mainly.
Journal ArticleDOI
Boron distribution in 9–12% chromium steels
TL;DR: In this article, the atom probe technique was used to clarify the distribution of boron in the microstructure of 9-12% chromium steels, and it was found that only very small amounts remained dissolved in the matrix after completed heat treatment (solution treatment and tempering).