Internal Friction Study on Mn-Ni-Enriched Precipitates
Induced by Thermal Aging in RPV Model Steel
Ting Hao 1*,
Yinxing Wu 1,2, Xianping Wang 1, Qianfeng Fang 1,
Xiangbing Liu 3, Yuanfei Li 3, Fei Xue 3
1 Institute of Solid State
Physics, Chinese Academy of Sciences, Hefei 230031, China
2 School of Materials and
Chemical Engineering, Anhui Jianzhu University, Hefei 230601, China
3 Suzhou Nuclear PowerResearch
Institute,Suzhou 215004,China
ABSTRACT : Irradiation-induced
MnNi-enriched precipitates (MNPs) are the main cause of irradiation
embrittlement in low-copper/copper-free reactor pressure vessel (RPV) steel. In
this work, the precipitation and re-dissolution process of MNPs induced by
thermal aging (400 °C, 500 °C, 600 °C and 700 °C for 200h, respectively) in Fe-1.35%Mn-0.74%Ni-0.19%Si
(mass%) RPV model steel were studied by means of the internal friction method
(IF), tensile and nano-hardness tests and so on. The IF measurement results
show a phenomenon that an IF peak relating to grain boundary (GB) sliding appears
(initial sample, aging at 400°C) - disappears (aging at 500°C, 600°C) -
reappears (aging at 700°C) with increasing isothermal aging temperature.
Tensile strength and nano-hardness results show as well that there are distinct
changes in the samples aged at 500°C, 600°C. It is concluded that the
disappearance of the IF peak may be due to the precipitation of MNPs at GBs in
the samples aged at 500 ° C, 600 °C, which hinder the GB sliding, while the
subsequent reappearance of IF peak in the sample aged at 700 °C may result from
the re-dissolution of MNPs.
Keywords: RPVsteel, Mn-Ni-enriched precipitate, thermal aging, internal friction, grain boundary relaxation
Ting Hao had gained his PhD in 2004 from the University of Tsukuba, Japan, and then worked at Hiroshima University, IMR at Tohoku University and Japan Atomic Energy Agency (JAEA), as a postdoctoral fellow. Now he is a professer of materials science at the Institute of Solid State Physics, Chinese Academy of Sciences. He has been working on metal materials and nuclear materials for more than ten years and has published more than 40 papers in reputed journals.