TY - JOUR
T1 - Effects of thermal aging on microstructure and hardness of stainless steel weld-overlay claddings of nuclear reactor pressure vessels
AU - Takeuchi, T.
AU - Kakubo, Y.
AU - Matsukawa, Y.
AU - Nozawa, Y.
AU - Toyama, T.
AU - Nagai, Y.
AU - Nishiyama, Y.
AU - Katsuyama, J.
AU - Yamaguchi, Y.
AU - Onizawa, K.
AU - Suzuki, M.
N1 - Funding Information:
This study was carried out under the Cooperative Research Program of the International Research Center for Nuclear Materials Science, the Institute for Materials Research (IMR), Tohoku University. Some of the results discussed here are those from the “Study of degradation mechanism of stainless steel weld-overlay cladding of nuclear reactor pressure vessels,” sponsored by the Strategic Promotion Program for Basic Nuclear Research of the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan. This study was partially supported by a Grant-in-Aid for Scientific Research (A) (21246142) from MEXT and by the Budget for Nuclear Research of MEXT, after screening and counseling by the Atomic Energy Commission, Japan. The authors would like to thank T. Kojima, H. Terashima, and M. Ono of JFE Techno-Research Corporation for their fabrication of the claddings.
PY - 2014/9
Y1 - 2014/9
N2 - The effects of thermal aging of stainless steel weld-overlay claddings of nuclear reactor pressure vessels on the microstructure and hardness of the claddings were investigated using atom probe tomography and nanoindentation testing. The claddings were aged at 400 °C for periods of 100-10,000 h. The fluctuation in Cr concentration in the δ-ferrite phase, which was caused by spinodal decomposition, progressed rapidly after aging for 100 h, and gradually for aging durations greater than 1000 h. On the other hand, NiSiMn clusters, initially formed after aging for less than 1000 h, had the highest number density after aging for 2000 h, and coarsened after aging for 10,000 h. The hardness of the δ-ferrite phase also increased rapidly for short period of aging, and saturated after aging for longer than 1000 h. This trend was similar to the observed Cr fluctuation concentration, but different from the trend seen in the formation of the NiSiMn clusters. These results strongly suggest that the primary factor responsible for the hardening of the δ-ferrite phase owing to thermal aging is Cr spinodal decomposition.
AB - The effects of thermal aging of stainless steel weld-overlay claddings of nuclear reactor pressure vessels on the microstructure and hardness of the claddings were investigated using atom probe tomography and nanoindentation testing. The claddings were aged at 400 °C for periods of 100-10,000 h. The fluctuation in Cr concentration in the δ-ferrite phase, which was caused by spinodal decomposition, progressed rapidly after aging for 100 h, and gradually for aging durations greater than 1000 h. On the other hand, NiSiMn clusters, initially formed after aging for less than 1000 h, had the highest number density after aging for 2000 h, and coarsened after aging for 10,000 h. The hardness of the δ-ferrite phase also increased rapidly for short period of aging, and saturated after aging for longer than 1000 h. This trend was similar to the observed Cr fluctuation concentration, but different from the trend seen in the formation of the NiSiMn clusters. These results strongly suggest that the primary factor responsible for the hardening of the δ-ferrite phase owing to thermal aging is Cr spinodal decomposition.
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U2 - 10.1016/j.jnucmat.2014.04.003
DO - 10.1016/j.jnucmat.2014.04.003
M3 - Article
AN - SCOPUS:84901854045
SN - 0022-3115
VL - 452
SP - 235
EP - 240
JO - Journal of Nuclear Materials
JF - Journal of Nuclear Materials
IS - 1-3
ER -