Production and Properties of Nano-scale Oxide Dispersion Strengthened (ODS) 9Cr Martensitic Steel Claddings

Ukai, Shigeharu; Kaito, Takeji; Ohtsuka, Satoshi; Narita, Tsuyoshi; Fujiwara, Masayuki; Kobayashi, Toshimi

doi:10.2355/isijinternational.43.2038

Cited by 90 publications

(66 citation statements)

References 11 publications

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“…In this study, the transformable martensitic base 12CrODS steels are designed to lead to better processing formability by the α/γ transformation. For transformable 9CrODS steels, it is known that their structure is a dual phase composed of tempered martensite and ferrite [4][5][6], although the full-tempered martensite is predicted in the equilibrium phase diagram. This ferrite is designated as a metastable residual ferrite, and it is also known that the residual ferrite significantly improves the high-temperature strength in 9CrODS steels [7][8][9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Residual ferrite formation in 12CrODS steels

Ukai

Kudo

et al. 2014

Journal of Nuclear Materials

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Increasing Cr content from 9 to 12 mass % leads to superior corrosion and high-temperature oxidation resistances, but usually changes microstructure from martensite to full-ferrite. Alloy design was conducted for 12CrODS steels to modify their structure to the martensite-base matrix, since the transformable martensititic ODS steels have superior processing capability by using α/γ phase transformation. The two types of ferrite are included; the equilibrium ferrite is predictable from the equilibrium phase diagram. Formation of the metastable residual ferrite was assessed through pinning of α/γ interfacial boundaries by oxide particles as well as chemical driving force for the α to γ transformation.

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Section: Introductionmentioning

confidence: 99%

Residual ferrite formation in 12CrODS steels

Ukai

Kudo

et al. 2014

Journal of Nuclear Materials

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“…9Cr-1Mo steel, PNC-FMS and so on. 1,2) It is widely recognized that these desirable properties are attributable to nano-size Y-Ti-O complex oxide particles dispersed in the matrix which act as obstacles to movement of dislocations. A high density of nano-size YTi-O complex oxide particles is produced by mechanically alloying (MA) Fe-Cr-Ti powders with Y 2 O 3 followed by hot-solidification process.…”

Section: Introductionmentioning

confidence: 99%

Kinetic Approach for Growth and Coalescence of Nano-Size Oxide Particles in 9Cr-ODS Steel Using High-Energy Synchrotron Radiation X-rays in SPring-8

et al. 2009

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Nanometer size oxide particles in 9Cr-ODS steel are dispersed finely and densely in a matrix by the hot-solidification process. The size and density distribution of dispersed oxide particles is recognized as one of the main issues for ensuring good microstructural stability and high temperature strength in a high temperature (<700 C) and neutron irradiation (250 dpa) environment. However, the behavior of oxide particles in the hot-solidification process has not been determined yet. This study evaluated the correlation between nano-size oxide particles and the heat treatment temperature and time in order to characterize the mechanism of formation and the behavior during growth and coalescence of these particles in 9Cr-ODS steel raw powder. XRD and SAXS measurements were made using high-energy synchrotron radiation X-rays in SPring-8. This is the first report of the oxide complex particles (Y 2 Ti 2 O 7 and Y 2 TiO 5 ) being formed from 800 to 960 C, and they were observed to grow and coalesce on increasing both heat-treatment temperature and time.

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“…In addition, our studies revealed that -ferrite formation in tempered martensite considerably improves the creep strength of 9Cr-ODS steel. [2][3][4][5][6] As for the conventional martensitic steels, -ferrite is a detrimental phase which never acts as reinforcement phase, so that the martensite single phase matrix is preferentially chosen. However, the -ferrite in 9Cr-ODS steel is believed to be a reinforcement phase because it appears to contain higher population of nano-size oxide particles than tempered martensite.…”

Section: Introductionmentioning

confidence: 99%

“…However, the -ferrite in 9Cr-ODS steel is believed to be a reinforcement phase because it appears to contain higher population of nano-size oxide particles than tempered martensite. [2][3][4][5][6] The 9Cr-ODS steel has the complex dual-phase microstructure consisting of fine ferrite and martensite grains, in which many oxide particles are dispersed in nanometer scale. Then, it is difficult to derive trustworthy information on ferrite proportion and morphology by conventional technique such as metallographic observation.…”

Section: Introductionmentioning

confidence: 99%

“…[1][2][3][4] In Fast Reactor Cycle Technology Development (FaCT) project promoted by JAEA, the 9Cr-ODS steel is ranked as the primary candidate for commercialized Fast Breeder Reactor (FBR) fuel cladding tube that will be exposed to maximum temperature of 973 K and peak neutron dose up to 250 dpa. 4) It is known that noticeable strengthening factor of 9Cr-ODS steel is the high number density of dispersed oxide particles.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Nano-Size Oxide Particle Dispersion and δ-Ferrite Proportion on Creep Strength of 9Cr-ODS Steel

et al. 2009

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The effects of chemical compositions on the microstructure and high-temperature creep strength of 9Cr-ODS steel was discussed in the light of quantitative data of -ferrite proportion and nano-size oxide particle dispersion, which were evaluated by dilatometric analysis and small angle neutron/X-ray scattering analysis, respectively. These quantitative data are well consistent with the conventional data obtained by transmission electron microscope. Both data indicate that the important microstructural feature for creep strength improvement of the 9Cr-ODS steel is the number density of nano-size oxide particles, and ferrite/martensite (F/M) duplex structure is favorable for high population nano-size oxide particle dispersion. Both optimization of excess oxygen concentration and control of the F/M duplex structure are promising technique for nano-structure control of 9Cr-ODS steel. Tungsten solid solution strengthening appears to be small compared with oxide dispersion strengthening enhanced by duplex microstructure formation.

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Production and Properties of Nano-scale Oxide Dispersion Strengthened (ODS) 9Cr Martensitic Steel Claddings

Cited by 90 publications

References 11 publications

Residual ferrite formation in 12CrODS steels

Residual ferrite formation in 12CrODS steels

Kinetic Approach for Growth and Coalescence of Nano-Size Oxide Particles in 9Cr-ODS Steel Using High-Energy Synchrotron Radiation X-rays in SPring-8

Effect of Nano-Size Oxide Particle Dispersion and δ-Ferrite Proportion on Creep Strength of 9Cr-ODS Steel

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Production and Properties of Nano-scale Oxide Dispersion Strengthened (ODS) 9Cr Martensitic Steel Claddings

Cited by 90 publications

References 11 publications

Residual ferrite formation in 12CrODS steels

Residual ferrite formation in 12CrODS steels

Kinetic Approach for Growth and Coalescence of Nano-Size Oxide Particles in 9Cr-ODS Steel Using High-Energy Synchrotron Radiation X-rays in SPring-8

Effect of Nano-Size Oxide Particle Dispersion and &delta;-Ferrite Proportion on Creep Strength of 9Cr-ODS Steel

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Effect of Nano-Size Oxide Particle Dispersion and δ-Ferrite Proportion on Creep Strength of 9Cr-ODS Steel