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Journal Articles

Tensile overload-induced texture effects on the fatigue resistance of a CoCrFeMnNi high-entropy alloy

Lam, T.-N.*; Chin, H.-H.*; Zhang, X.*; Feng, R.*; Wang, H.*; Chiang, C.-Y.*; Lee, S. Y.*; Kawasaki, Takuro; Harjo, S.; Liaw, P. K.*; et al.

Acta Materialia, 245, p.118585_1 - 118585_9, 2023/02

 Times Cited Count:2 Percentile:62.4(Materials Science, Multidisciplinary)

Journal Articles

Synchrotron radiation X-ray diffraction method

Hayashi, Makoto*; Shobu, Takahisa

Residual Stress, p.100 - 132, 2021/00

Structural materials may undergo fatigue fracture or stress corrosion cracking during use. One of the causes is the residual stress generated by heat treatment and processing in the manufacturing process of structural materials. There are various methods for measuring the residual stress. This book introduces measurement techniques using ultrasonic and magnetic methods, starting with laboratory X-rays, synchrotron radiation X-rays, and neutrons. In addition, we will outline examples of measurement of residual stress due to processing and welding of various materials, measurement examples of actual machines, change behavior of residual stress due to static and repeated loads, and evaluation methods of fatigue remaining life based on the change behavior.

Journal Articles

Thermal fatigue test on dissimilar welded joint between Gr.91 and 304SS

Wakai, Takashi; Kobayashi, Sumio; Kato, Shoichi; Ando, Masanori; Takasho, Hideki*

Proceedings of 25th International Conference on Nuclear Engineering (ICONE-25) (CD-ROM), 7 Pages, 2017/07

This paper describes a thermal fatigue test on a structural model with a dissimilar welded joint. In the present design of JSFR, there may be dissimilar welded joints between ferritic and austenitic steels especially in IHX and SG. Creep-fatigue is one of the most important failure modes in JSFR components. However, the creep-fatigue damage evaluation method has not been established for dissimilar welded joint. To investigate the evaluation method, structural test will be needed for verification. Therefore, a thermal fatigue test on a thick-wall cylinder with a circumferential dissimilar welded joint between Mod.9Cr-1Mo steel and 304SS was performed. Since the coefficients of thermal expansion of these steels were significantly different, buttering layer of Ni base alloy was installed between them. After the completion of the test, deep cracks were observed at the HAZ in 304SS, as well as at HAZ in Mod.9Cr-1Mo steel. There were many tiny surface cracks in BM of 304SS. According to the fatigue damage evaluation based on the finite element analysis results, the largest fatigue damage was calculated at HAZ in 304SS. Large fatigue damage was also estimated at BM of 304SS. Fatigue cracks were observed at HAZ and BM of 304SS in the test, so that analytical results are in a good agreement with the observations. However, though relatively small fatigue damage was estimated at HAZ in Mod.9Cr-1Mo steel, deep fatigue cracks were observed in the test. To identify the cause of such a discrepancy between the test and calculations, we performed a series of finite element analyses. Some metallurgical investigations were also performed.

Journal Articles

Creep-fatigue tests of double-end notched bar made of Mod.9Cr-1Mo steel

Shimomura, Kenta; Kato, Shoichi; Wakai, Takashi; Ando, Masanori; Hirose, Yuichi*; Sato, Kenichiro*

Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 9 Pages, 2015/05

This paper describes experimental and analytical works to confirm that the design standard for SFR components sufficiently covers possible failure mechanisms. Creep-fatigue damage evaluation method in JSME design standard for SFR components has been constructed based on experiments and/or numerical analyses of conventional austenitic stainless steels, such as 304SS. Since the material characteristics of Mod.9Cr-1Mo steel are substantially different from those of austenitic stainless steels, it is required to verify the applicability of the design standards to the SFR components made of Mod.9Cr-1Mo steel. A series of uni-axial creep-fatigue tests were conducted using double-ended notch bar specimens made of Mod.9Cr-1Mo steel under displacement controlled condition with 30 minute holding. The curvature radii of the specimens were 1.6mm, 11.2mm and 40.0mm. The specimen having 1.6mm notch and 11.2mm notch failed from outer surface but the specimen having 40.0mm notch showed obvious internal crack nucleation. In addition, though total duration time of the creep-fatigue test was only 2,000 hours, a lot of creep voids and inter granular crack growth were observed. To clarify the cause of such peculiar failure, some additional experiments were performed, as well as some numerical analyses. We could point out that such a peculiar failure aspect might result from corresponding stress distribution in the cross section. As a result of a series of investigations, possible causes of such peculiar failure could be narrowed down. A future investigation plan was proposed to clarify the most significant cause.

Journal Articles

Thermal fatigue experiment of screw cooling tube under one-sided heating condition

Ezato, Koichiro; Suzuki, Satoshi; Sato, Kazuyoshi; Akiba, Masato

Journal of Nuclear Materials, 329-333(1), p.820 - 824, 2004/08

 Times Cited Count:6 Percentile:40.92(Materials Science, Multidisciplinary)

This paper presents thermal fatigue experiments of a cooling tube with a helical triangular fin on its inner cooled surface, namely a ${it screw tube}$. The screw thread is directly shaped in a CuCrZr heat sink bar as a cooling channel. Slits with the width of 1.5 mm are machined at the heated side of the heat sink. The thermal fatigue experiments are carried out at 20 and 30 $$rm MW/m^2$$ by using an electron beam irradiation facility in JAERI. Water leakages from fatigue cracks, which locate at the slit of the heat sink, occurred at around 4500th and 1400th cycles at 20 and 30 $$rm MW/m^2$$, respectively. These results show good agreement with lifetime predictions using Manson-Coffin's law based on finite element analyses. Fractographic observations reveal that the fatigue cracks start from the outer heated surface at the slit region of the cooling channel and propagate toward its inner surface.

JAEA Reports

Report on investigation of cause of crack at instrumentation pipe in JMTR; Data book on examination of pressure instrumentation pipe at JMTR hot laboratory

Working Group for Investigation of Cause of Crack Initiation

JAERI-Tech 2003-060, 183 Pages, 2003/07

JAERI-Tech-2003-060.pdf:55.37MB

On December 10, 2002, the water leakage was found at the pressure instrumentation pipe attached to the exit pipe of No.1 charging pump of the purification system of a primary cooling system at JMTR, and the cracks were detected on the pressure instrumentation pipe by the visual observation. The Investigation Committee for Water Leakage from Instrumentation Pipe in JMTR was established and organized by specialists from inside and outside JAERI on December 16. In order to investigate the cause of crack initiation at the pressure instrumentation pipe, the Working Group was organized in the Department of JMTR. Visual inspection, fractgraphy test, metallographic observation and hardness test for the pressure instrumentation pipe and its weldment were carried out in the JMTR Hot Laboratory. This report summarized above data obtained by investigation on the cause of the crack initiation.

Journal Articles

Difference in corrosion fatigue behavior between Ti-5Ta alloy and zirconium in boiling nitric acid

Motooka, Takafumi; Kiuchi, Kiyoshi

Corrosion, 58(8), p.703 - 709, 2002/08

 Times Cited Count:11 Percentile:57.69(Materials Science, Multidisciplinary)

Ti-5Ta alloy and zirconium with excellent corrosion resistance to nitric acid have been used as equipment materials in spent fuel reprocessing plants. However, zirconium has the susceptibility to stress corrosion cracking in nitric acid solutions. The fatigue crack growth rates of both metals were examined to clarify the effect of stress corrosion cracking on the fatigue crack growth in boiling 17% nitric acid. The fatigue crack growth behavior of Ti-5Ta alloy in nitric acid showed almost the same behavior as seen in air. The crack growth rate is slightly enhanced in nitric acid. The fracture surface showed the ductile striation with independence on the loading direction. On the other hand, the fatigue crack growth rate of zirconium is remarkably accelerated in nitric acid. The fatigue crack growth was affected by the cracking mode composed of the pseudo-cleavage and plastic deformation. The difference in fatigue cracking behavior on both metals in nitric acid is interpreted with the difference in a cross slip system and the corrosion resistance in nitric acid.

Journal Articles

Corrosion fatigue growth of zirconium in boiling nitric acid

Motooka, Takafumi; Kiuchi, Kiyoshi

Corrosion, 58(6), p.535 - 540, 2002/06

 Times Cited Count:5 Percentile:40.1(Materials Science, Multidisciplinary)

The fatigue crack growth of a commercial grade zirconium has been studied in boiling nitric acid and in air at room temperature under tensile load control. The fatigue crack growth rate in air is strongly dependent on the crystallographic texture. It is interpreted based on the crystal anisotropy on mechanical strength in the hexagonal closed pack structure of zirconium. The fatigue crack growth rate in nitric acid is about four times higher than that in air. Texture is found to have an effect on the fracture path in nitric acid. Microfractography of the fracture surfaces shows that the corrosion fatigue growth has a characteristic mechanism. The fracture surface consists of a mixture of grains: some broken by pseudo-cleavage as seen in stress corrosion cracking, and the others broken by fatigue with striation as seen in air. In the low crack growth rate regime pseudo-cleavage is dominant, whereas in the high crack growth rate regime the main fracture mode is ductile fracture.

Journal Articles

Corrosion fatigue of refractory materials in boiling nitric acid

Motooka, Takafumi; Kiuchi, Kiyoshi

Materials Transactions, 43(5), p.1220 - 1224, 2002/05

 Times Cited Count:2 Percentile:23.99(Materials Science, Multidisciplinary)

Refractory materials such as zirconium, niobium and titanium alloys with excellent corrosion resistance in boiling nitric acid have been selected for use as structural materials of spent fuel reprocessing equipment. The fatigue crack growth rates of these materials were investigated by load control tests as a function of the stress intensity factor range in boiling 3N nitric acid and in air at room temperature. The fracture surfaces were observed by SEM. The fatigue crack growth rates of zirconium and niobium were enhanced in boiling nitric acid compared with those in air at room temperature. Acceleration effect due to corrosion fatigue was not observed in the crack growth of Ti-5Ta alloy. The fracture surfaces of Ti-5Ta alloy showed the ductile striation in both environments. On the other hand, the fracture surfaces of niobium represented the fatigue striation in air and the brittle striation due to corrosion in nitric acid. The fracture surfaces of zirconium in nitric acid showed brittle fracture and the ductile fracture related to stress corrosion cracking.

Journal Articles

Corrosion fatigue of refractory materials with corrosion resistance to boiling nitric acid

Motooka, Takafumi; Kiuchi, Kiyoshi

Proceedings of the 2nd International Conference on Environment Sensitive Cracking and Corrosion Damage (ESCCD 2001), p.374 - 378, 2001/11

Refractory metals such as Zr, Nb and Ti alloys with the excellent corrosion resistance in boiling nitric acid have been selected for structural materials of spent fuel reprocessing equipment. On this study, the fatigue crack growth rate of these materials was investigated by load control tests as a function of the stress intensity in boiling nitric acid and in air at room temperature. The fracture surface was observed by scanning electron microscopy. The crack growth rate of Zr and Nb was enhanced in boiling nitric acid compared with that in air at room temperature. Acceleration effect due to corrosion fatigue was not observed in the crack growth of Ti-5Ta alloy. The fracture surfaces of Ti-5Ta alloy showed the ductile striation in both environments. On the other hand, the fracture surfaces of Nb showed the ductile striation in air and brittle striation in nitric acid. The anodic dissolution was interpreted to the acceleration factor on corrosion fatigue of Nb. The fracture surfaces of Zr in nitric acid showed both brittle and ductile fracture with fluted pattern due to SCC.

Journal Articles

Effect of thermal history on tensile and fatigue crack growth properties of a cryogenic austenitic stainless steel forged at room and liquid helium temperatures

*; *; O.Ivano*; Nunoya, Yoshihiko; Nakajima, Hideo; Tsuji, Hiroshi

Zairyo, 45(1), p.38 - 42, 1996/01

no abstracts in English

Journal Articles

Effect of sensitizing heat treatment on fatigue crack growth properties at liquid helium temperature

*; *; O.Ivano*; Nunoya, Yoshihiko; Nakajima, Hideo; Tsuji, Hiroshi

Fatigue & Fracture of Engineering Materials & Structures, 18(6), p.671 - 678, 1995/00

 Times Cited Count:1 Percentile:19.21(Engineering, Mechanical)

no abstracts in English

Journal Articles

Influence of wetting effect at the outer surface of the pipe on increase in leak rate; Experimental results and discussion

Isozaki, Toshikuni; Shibata, Katsuyuki

LBB95: Specialist Meeting on Leak Before Break in Reactor Piping and Vessels, 0, 10 Pages, 1995/00

no abstracts in English

Journal Articles

Evaluation of LBB in piping considering multiple fatigue crack growth

Shibata, Katsuyuki

Zairyo Rikigaku Koenkai Koen Rombunshu, Vol.B, p.149 - 151, 1991/00

no abstracts in English

JAEA Reports

Development of leak analysis programs from through-wall crack

; Shibata, Katsuyuki; Isozaki, Toshikuni

JAERI-M 90-050, 106 Pages, 1990/03

JAERI-M-90-050.pdf:2.17MB

no abstracts in English

Journal Articles

The crack initiation and growth behavior for high temperature creep-fatigue interaction in notched specimen of Ni-based alloy

; *; ;

Nihon Kikai Gakkai Rombunshu, A, 52(477), p.1228 - 1231, 1986/00

no abstracts in English

Journal Articles

Study on growth evaluation for surface cracks, I; Fatigue behavior of flat plate specimen with surface cracks and Evaluation of crack growth behavior

; ; *; ;

Nihon Genshiryoku Gakkai-Shi, 27(3), p.250 - 261, 1985/00

 Times Cited Count:13 Percentile:81.95(Nuclear Science & Technology)

no abstracts in English

JAEA Reports

Cyclic Crack Growth Typical Weld HAZ Microstructures of SA 533gr.B Steel in Simulated BWR Environment

; ; Shindo, Masami; ; ; ; ; ; *; *; et al.

JAERI-M 82-062, 23 Pages, 1982/06

JAERI-M-82-062.pdf:1.31MB

no abstracts in English

28 (Records 1-20 displayed on this page)