Effects of thermal aging on microstructure and hardness of stainless steel weld-overlay claddings of nuclear reactor pressure vessels

Takeuchi, Tomoaki; Kakubo, Yuta*; Matsukawa, Yoshitaka*; Nozawa, Yasuko*; Toyama, Takeshi*; Nagai, Yasuyoshi*; Nishiyama, Yutaka; Katsuyama, Jinya; Yamaguchi, Yoshihito; Onizawa, Kunio; et al.

Journal of Nuclear Materials, 452(1-3), p.235 - 240, 2014/09

https://doi.org/10.1016/j.jnucmat.2014.04.003

Microstructures and hardness of stainless steel weld overlay cladding of reactor pressure vessels subjected to the thermal aging at 400 C for 100-10,000 h were investigated using atom probe tomography and nanoindentation technique. The Cr concentration fluctuation in the -ferrite phase caused by spinodal decomposition rapidly progressed by the 100 h aging while NiSiMn clusters increased in number density at 2,000 h and coarsened at 10,000 h. The hardness of the -ferrite phase also rapidly increased at the short aging time. The Cr concentration fluctuation and the hardness were in good correlation with the degree of the Cr concentration fluctuation rather than the formation of the NiSiMn clusters. These results strongly suggested that the dominant factor of the hardening of the -ferrite phase by the thermal aging was Cr spinodal decomposition.

Effect of neutron irradiation on the microstructure of the stainless steel electroslag weld overlay cladding of nuclear reactor pressure vessels

Takeuchi, Tomoaki; Kakubo, Yuta*; Matsukawa, Yoshitaka*; Nozawa, Yasuko*; Nagai, Yasuyoshi*; Nishiyama, Yutaka; Katsuyama, Jinya; Onizawa, Kunio; Suzuki, Masahide

Journal of Nuclear Materials, 443(1-3), p.266 - 273, 2013/11

https://doi.org/10.1016/j.jnucmat.2013.07.035

Investigation on irradiation effects of weld-overlay claddings is necessary for safety assessment of reactor pressure vessels. We investigated microstructural changes in the cladding, which was composed of about 90% austenite and 10% -ferrite phases, subjected to the neutron irradiation to 7.210 n/cm at 290C, by 3D atom probe tomography technique. In the ferrite phase, the amplitude of the Cr and Si concentration fluctuation was increased by the irradiation and Ni and Mn concentration fluctuations were newly occurred. In the austenite phase, '(NiSi) -like clusters were formed. In contrast, the results of our previous work on the cladding subjected to thermal aging showed the amplitude of the Cr fluctuation was significantly increased and G (Ni-Si-Mn) phase was formed in the ferrite phase. Moreover, no changes were observed in the austenite by the aging.

An Ion channeling study on VD crystals

Yamaguchi, Sadae*; Takahiro, K.*; Fujino, Yutaka*; Naramoto, Hiroshi; Ozawa, Kunio*

Journal of Alloys and Compounds, 231, p.132 - 137, 1995/00

https://doi.org/10.1016/0925-8388(95)01787-9

no abstracts in English

Bibliographic data on surface processes in particle-material interactions published in Japan; 1986-1987

Geshi, Kazuo; Nagai, Shiro; Ozawa, Kunio*

JAERI-M 88-268, 130 Pages, 1989/01

JAERI-M-88-268.pdf:2.68MB

no abstracts in English

Damage profiles in alkali halides irradiated with high-energy heavy ions

*; Naramoto, Hiroshi; Ozawa, Kunio*;

Nuclear Instruments and Methods in Physics Research B, 39, p.724 - 727, 1989/00

https://doi.org/10.1016/0168-583X(89)90883-5

no abstracts in English

Ag-sheathed high T superconducting tape with J=10 A/cm

; *; *; *; *; *; *; Ozawa, Kunio; Morii, Yukio; Funahashi, Satoru

Proc. on the ISTEC Workshop on Superconductivity, p.111 - 114, 1989/00

no abstracts in English

Ion-impact desorption

*; Nagai, Shiro; Ozawa, Kunio*

JAERI-M 88-146, 113 Pages, 1988/08

JAERI-M-88-146.pdf:1.9MB

no abstracts in English

Correlation between charge states and scattering angles of 150MeV C1 ions exiting from carbon foils

*; *; Kawatsura, Kiyoshi; Sataka, Masao; Ozawa, Kunio*; Komaki, Kenichiro*; *; *

Nuclear Instruments and Methods in Physics Research B, 33, p.230 - 234, 1988/00

https://doi.org/10.1016/0168-583X(88)90554-X

no abstracts in English

Spectral data and Grotrian diagrams for highly ionized nickel Ni IX - Ni XXVIII

Shirai, Toshizo; *; Sugar, J.*; Wiese, W. L.*; Nakai, Yota; Ozawa, Kunio*

Atomic Data and Nuclear Data Tables, 37(2), p.235 - 332, 1987/00

https://doi.org/10.1016/0092-640X(87)90021-0

no abstracts in English

3DAP analysis of a neutron-irradiated stainless steel weld-overlay cladding of nuclear reactor pressure vessel

Takeuchi, Tomoaki; Nishiyama, Yutaka; Katsuyama, Jinya; Onizawa, Kunio; Nozawa, Yasuko*; Matsukawa, Yoshitaka*; Toyama, Takeshi*; Nagai, Yasuyoshi*; Kameda, Jun*

no journal, , 

Microstructure evolution on stainless overlay cladding of reactor pressure vessel was quantitatively investigated by means of three-dimensional local electrode atom probe (3DAP) in nano-scale. The cladding material was neutron-irradiated up to 710 n/cm (E 1 MeV) at JMTR. In ferrite phases of cladding material, a 12% of Cr concentration fluctuation, which was arisen through a spinodal decomposition, observed before the irradiation was progressed to 20% after the irradiation while the wave length of the fluctuation was almost not changed about 8-10 nm before and after the irradiation. In addition, Ni, Si and Mn concentration fluctuations were also observed. The concentration fluctuations of the elements other than Cr and differences from the thermal aging will be reported in presentation.