Change in mechanical properties by high-cycle loading up to Gigacycle for 316L stainless steel

Naoe, Takashi; Harjo, S.; Kawasaki, Takuro; Xiong, Z.*; Futakawa, Masatoshi

JPS Conference Proceedings (Internet), 28, p.061009_1 - 061009_6, 2020/02

https://doi.org/10.7566/JPSCP.28.061009

At the J-PARC, a mercury target vessel made of 316L SS suffers proton and neutron radiation environment. The target vessel also suffers cyclic impact stress caused by the proton beam-induced pressure waves. The vessel suffers higher than 4.510 cyclic loading during the expected service life of 5000 h. We have investigated fatigue strength 316L SS up to gigacycle in the previous studies. The cyclic hardening and softening behavior were observed. In this study, to evaluate the cyclic hardening/softening behavior, the dislocation densities of specimens were measured using the neutron diffraction method at the MLF BL-19. The result showed that the dislocation density of a 316L SS was increased with increasing the number of loading cycles. By contrast, in the case of cold-rolled 316L SS, annihilation and re-accumulation of dislocation by cyclic loading were observed. In the workshop, result of neutron diffraction measurement will be introduced with the progress of fatigue test.

Improved cavitation resistance of structural materials in pulsed liquid metal targets by surface hardening

Koppitz, T.*; Jung, P.*; Mller, G.*; Weisenburger, A.*; Futakawa, Masatoshi; Ikeda, Yujiro

Journal of Nuclear Materials, 343(1-3), p.92 - 100, 2005/08

https://doi.org/10.1016/j.jnucmat.2004.08.034

Cavitation damage of structural materials due to pressure waves is expected to be one of the majior life-time limiting factors in high power liquid metal spallation targets under pulsed operation. Two methods are developed for the European Spallation Source (ESS) to mitigate this damage: Introduction of gas bubbles to surpress the pressure pulse and surface-hardening of structural materials. Surface-hardening of four 8-13%Cr martenstic steels was examined by thermal treatment with pulsed or scanned electron- and laser-beams as well as by nitriding in plasma. A specimens of the 12%Cr steel were tested in liquid mercury under pulsed proton irradiation, and under mechanical pulsed-loading. Surface damage was analysed by optical, confocal-laser, or scanning-electron microscopy, showing in both tests much better resistance of the hardened material compared to standard condition.

Hardening of Fe-Cu model alloys induced by electron irradiation and neutron irradiation

Tobita, Toru; Aizawa, Kazuya; Suzuki, Masahide; Iwase, Akihiro*

Nihon Genshiryoku Gakkai Wabun Rombunshi, 3(4), p.331 - 339, 2004/12

https://doi.org/10.3327/taesj2002.3.331

Nevertheless, there is a possibility that -ray induces embrittlement more efficiently than fast neutron, the irradiation effect of -ray has not been fully clarified. Comparative experiments on irradiation hardening by 2.5MeV electron irradiation for the purpose of -ray irradiation and neutron irradiation were performed to the Fe-Cu model alloys. We obtained the dose dependence and the temperature dependence on irradiation induced hardening. The growth of Cu clusters with increase in irradiation dose was confirmed by the small angle neutron scattering measurements. Although the differences in hardening between electron and neutron irradiations were very small on a displacement-per-atom (dpa) basis, the electron irradiation hardening initiated slightly earlier than the neutron. The growth of Cu clusters with increase in irradiation dose was the principal cause of hardening. The present results suggested that, from an engineering point of view, both the -ray induced and neutron induced hardening can be well scaled by using dpa.

Report of Examination of the Sample from Core Shroud (O1-H2) at Onagawa Nuclear Power Station Unit-1 (Contract research)

The Working Team for Examination of the Sample from Core Shrouds and Primary Loop Recirculation Pipi

JAERI-Tech 2004-012, 62 Pages, 2004/02

JAERI-Tech-2004-012.pdf:16.4MB

At Onagawa Nuclear Power Station Unit-1 of the Tohoku Electric Power co., inc., cracks were confirmed near welded joints of core shroud in 15th periodical inspection. Tohoku Electric Power co., inc. has conducted a material examination with Nippon Nuclear Fuel Development Co., Ltd.. To investigate independently, a JAERI's own evaluation report was provided. The results are as follows; (1) Hardening layer was detected at the depth of about 150-250m from outer surface of the sample. (2) Corrosion products were observed on inner surface of the cracks and some of them penetrated into grains. (3) Transgranular cracking and intergranular cracking were observed at the region within about 100m and the deeper region more than about 200m in depth from outer surface of the sample, respectively. (4) Distinct chromium depletion was not detected at the grain boundaries. (5) Chemical compositions of the sample corresponded to type 304L stainless steel in Japanese Industrial Standard. From the above, it is concluded that the cracks are stress corrosion cracking.

Report of Examination of the Sample from Core Shroud (1F4-H4) at Fukushima Dai-ichi Nuclear Power Station Unit-4 (Contract research)

The Working Team for Examination of the Sample from Core Shrouds and Primary Loop Recirculation Pipi

JAERI-Tech 2004-004, 74 Pages, 2004/02

JAERI-Tech-2004-004.pdf:31.62MB

During the 12th periodical inspection in Fukushima Dai-ichi Nuclear Power Station Unit-4 (BWR, 784MW) of Tokyo Electric Power Company (TEPCO), which has been held from September 1993 to February 1994, cracks were found at welded joints No.H4 in the core shroud middle shell. TEPCO has conducted a material examination with Nippon Nuclear Fuel Development Co. Ltd. (NFD) on the SUS304L specimen including cracks sampled from the inner surface of welded joints (H4) of the middle shell of the core shroud. The present examination has been performed with the objective to independently investigate and evaluate the materials by jointly attending the examination with NFD, receiving the final data given by the examination and providing a JAERI's own evaluation report as a third-party organization for assuring the transparency. Based on the research results described above, presence of tensile residual stress by welding and relatively high dissolved oxygen contents in core coolant, it is concluded that the cracks observed were caused by the stress corrosion cracking (SCC).

Localized-impact damage caused by proton bombarding in mercury target

Futakawa, Masatoshi; Kogawa, Hiroyuki; Ishikura, Shuichi*; Kudo, Hisaaki*; Soyama, Hitoshi*

Journal de Physique, IV, 110, p.583 - 588, 2003/09

A liquid-mercury target system for the MW-scale target is being developed in the world. The moment the proton beams bombard the target, pressure waves will be generated in the mercury by the thermally shocked heat deposition. Provided that the negative pressure generates through its propagation in the mercury target and causes cavitation in the mercury, there is the possibility for the cavitation bubbles collapse to form pits on the interface between the mercury and the target vessel wall. In order to estimate the cavitation erosion damage, Split Hopkinson Pressure Bar (SHPB) tests impact tests were performed to impose the impact pressure to the interface between mercury and solid metals. In particular, the surface hardening treated samples: Kolsterising, some coatings are investigated. As results, it is confirmed that the pitting damage is suppressed by surface hardening treatments and relative hardness appeared to be a good correlating parameter on impact erosion resistance.

Irradiation embrittlement of 2.25Cr-1Mo steel at 400C and its electrochemical evaluation

Nishiyama, Yutaka; Fukaya, Kiyoshi; Suzuki, Masahide; Eto, Motokuni

Journal of Nuclear Materials, 258-263, p.1187 - 1192, 1998/00

https://doi.org/10.1016/S0022-3115(98)00184-6

no abstracts in English

Radiation effects in pure silica core and ge-doped silica core fibers

; ; *; *; *; *; *; *

Fujikura Densen Giho, 66, p.42 - 50, 1983/00

no abstracts in English

Strain growth behaviors due to thermal-stress ratiheting for a strain-hardening material; In the case of variable area ratio of hot to cold elements

Nihon Kikai Gakkai Rombunshu, A, 44(N0.379), p.816 - 824, 1978/00

no abstracts in English

The Role of some alloying elements on radiation hardening in pressure vessel steels

*; ; *

ASTM Special Technical Publication 529, p.63 - 74, 1973/00

https://doi.org/10.1520/STP35435S

no abstracts in English