中島 健次; Harjo, S.; 山田 悟史*; 及川 健一; 梶本 亮一
JAEA-Review 2018-032, 43 Pages, 2019/02
及川 健一; Su, Y.; 鬼柳 亮嗣; 川崎 卓郎; 篠原 武尚; 甲斐 哲也; 廣井 孝介; Harjo, S.; Parker, J. D.*; 松本 吉弘*; et al.
Physica B; Condensed Matter, 551, p.436 - 442, 2018/12
We are promoting for practical product observation by the energy-resolved neutron imaging method using high-intensity pulsed neutrons at J-PARC, under the Photon and Quantum Basic Research Coordinated Development Program from the Ministry of Education, Culture, Sports, Science and Technology, Japan. Bragg edge imaging, one of the energy-resolved neutron imaging methods for visualizing material properties, was applied to feasibility study of the temperature distribution of copper rod, complementary study of the texture and strain distribution of bent steel plates using neutron diffraction and EBSD, and so on. Outline of results obtained by these imaging experiments will be presented.
阿部 淳*; 関根 孝太郎*; Harjo, S.; 川崎 卓郎; 相澤 一也
Physica B; Condensed Matter, 551, p.283 - 286, 2018/12
Our previous neutron diffraction measurements investigated strain accumulation mechanism(s) in rock materials under uniaxial compression. This technique, when applied to metallic materials, is suffered by surface effects, gauge volume size effects, and/or incident beam divergence that induce pseudo-strain. Knowledge of the pseudo-strain is therefore necessary for precise evaluation of strain value in a stressed rock material. This work investigated the effects of gauge volume and incident neutron beam divergence on pseudo-strain in rock materials via neutron diffraction experiments performed on three types of sandstone. Spurious peak shifts appeared depending on the gauge volume or incident neutron beam divergence. These peak shifts were inferred to be derived from the difference between a neutron-weighted center of gravity position and a geometric center of the gauge volume position. However, changing the gauge volume height did not cause shift in the peak position.
Wang, B.*; He, H.*; Naeem, M.*; Lan, S.*; Harjo, S.; 川崎 卓郎; Nie, Y.*; Wang, X.-L.*; 他7名*
Scripta Materialia, 155, p.54 - 57, 2018/10
The deformation behavior of an equi-atomic face-centered-cubic CoCrFeNi high entropy alloy was investigated by in-situ neutron diffraction under tensile loading up to 40% applied strain. A three-stage deformation behavior was fully captured by lattice strain and texture evolution. In spite of the chemical complexity, the deformation in CoCrFeNi is dominated by dislocation activities. Analysis of diffraction and microscopy data shows that the deformation progresses from dislocation slip to severe entanglement, where a sharp increase in dislocation density was observed. The neutron diffraction data, corroborated by transmission electron microscopy analysis, provided microscopic insights of the previously reported three-stage hardening behavior.
川崎 卓郎; 稲村 泰弘; 伊藤 崇芳*; 中谷 健; Harjo, S.; Gong, W.*; 相澤 一也
Journal of Applied Crystallography, 51(3), p.630 - 634, 2018/06
A time-resolved time-of-flight neutron diffraction technique to characterize the structural properties of materials during cyclic tests has been developed. By adopting the developed technique, the behaviors of the crystal lattice and domains of the piezoelectric material in a multilayer-type piezoelectric actuator driven by a cyclic electric field were evaluated. The variation in diffraction intensity during the application of a cyclic electric field was obtained successfully, and the hysteresis-like behaviors of both the lattice strain and the 90 domain switching were revealed.
徐 平光; Harjo, S.; 小島 真由美*; 鈴木 裕士; 伊藤 崇芳*; Gong, W.; Vogel, S. C.*; 井上 純哉*; 友田 陽*; 相澤 一也; et al.
Journal of Applied Crystallography, 51(3), p.746 - 760, 2018/06
Neutron diffraction texture measurements provide bulk textures with excellent grain statistics even for large grained materials, together with the crystallographic parameters and microstructure information such as phase fractions, coherent crystallite size, root mean square microstrain, macroscopic/intergranular stress/strain. The procedure for high stereographic resolution texture and residual stress evaluation was established at the TAKUMI engineering materials diffractometer. The pole figure evaluation of a limestone standard sample with a trigonal crystal structure suggested that the obtained precision for texture measurement is comparable with the oversea well-established neutron beam lines utilized for texture measurements. A high strength martensite-austenite multilayered steel was employed for further verification of the reliability of simultaneous Rietveld analysis of multiphase textures and macro stress tensors. By using a geometric mean micro-mechanical model, the macro stress tensor analysis with a plane stress assumption showed a RD-TD in-plane compressive stress (about -330 MPa) in martensite layers and a RD-TD in-plane tensile stress (about 320 MPa) in austenite layers. The phase stress partitioning was ascribed to the additive effect of volume expansion during martensite transformation and the linear contraction misfit during water quenching.
鈴木 裕士; 楠 浩一*; 佐竹 高祐*; 兼松 学*; 小山 拓*; 丹羽 章暢*; 椛山 健二*; 向井 智久*; 川崎 卓郎; Harjo, S.
非破壊検査, 67(4), p.180 - 186, 2018/04
諏訪 友音*; 辺見 努*; 齊藤 徹*; 高橋 良和*; 小泉 徳潔*; Luzin, V.*; 鈴木 裕士; Harjo, S.
IEEE Transactions on Applied Superconductivity, 28(3), p.6001104_1 - 6001104_4, 2018/04
NbSn strands, whose properties are very sensitive to stress/strain, are utilized for ITER cable-in-conduit conductor (CICC) of the central solenoids. The NbSn strands experience temperature range of 1000 K from the temperature of the heat treatment with the initiation of the NbSn reaction to the operation temperature of 4 K. Due to this large temperature range, large thermal strain is induced in the NbSn filaments due to the differences between the coefficients of thermal expansion and Young's moduli of the components of the strand. Therefore, it is considered that initial performance of the CICC is influenced by the thermal strain on the NbSn, and it is important to evaluate the strain state of the NbSn strand at low temperature. In this study, the thermal strain of the components of free NbSn strand was measured by neutron diffraction and stress/strain state was assessed from room temperature to low temperature. As the results of diffraction measurements, it was found that 0.111 % and 0.209 % compressive strain were generated in NbSn filaments at 300 and 10 K, respectively.
中村 良彦*; 柴田 曉伸*; Gong, W.*; Harjo, S.; 川崎 卓郎; 伊東 篤志*; 辻 伸泰*
Proceedings of International Conference on Martensitic Transformations: Chicago, p.155 - 158, 2018/04
The microstructure evolution of medium manganese steel (Fe-5Mn-2Si-0.1C (wt%)) during thermo-mechanical processing in ferrite + austenite two-phase region was investigated by in situ neutron diffraction analysis and microstructure observations. When the specimens were isothermally held at a temperature of 700C, the fraction of reversely transformed austenite increased gradually with an increase in the isothermal holding time. However, it did not reach the equilibrium fraction of austenite even after isothermal holding for 10 ks. On the other hand, the fraction of reversely transformed austenite increased rapidly after the compressive deformation at a strain rate of 1 s at 700C and reached the equilibrium state during subsequent isothermal holding for around 3 ks.
牟田 浩明*; 西金 遼二*; 安藤 祐介*; 松永 純治*; 坂本 寛*; Harjo, S.; 川崎 卓郎; 大石 佑治*; 黒崎 健*; 山中 伸介*
Journal of Nuclear Materials, 500, p.145 - 152, 2018/03
Precipitation of brittle zirconium hydrides deteriorate the fracture toughness of the fuel cladding tubes of light water reactor. In the present study, to elucidate relationship between mechanical properties and microstructure, two -phase zirconium hydrides and one -phase zirconium hydride were carefully fabricated considering volume changes at the metal-to-hydride transformation. The -hydride that was fabricated from -zirconium exhibits numerous inner cracks due to the large volume change. Analyses of the neutron diffraction pattern and electron backscatter diffraction (EBSD) data show that the sample displays significant stacking faults in the plane and in the pseudo-layered microstructure. On the other hand, the -hydride sample fabricated from -zirconium at a higher temperature displays equiaxed grains and no cracks.
土田 紀之*; Harjo, S.
Proceedings of International Conference on Martensitic Transformations: Chicago, p.43 - 46, 2018/00
In order to investigate TRIP (transformation induced plasticity) effect in different deformation style, a room temperature creep test under the constant load was conducted by using a TRIP-aided multi-microstructure steel. As a result, the volume fraction of deformation-induced martensite in the constant load creep test was larger than that in the tensile test. In situ neutron diffraction experiments during the constant load creep test were performed to discuss its reason. It is found from the in situ neutron diffraction experiments during the constant load creep tests that the phase strain of the austenite phase in the creep tests was larger than that in the tensile tests at the same applied stress.
佐藤 成男*; 黒田 あす美*; 佐藤 こずえ*; 熊谷 正芳*; Harjo, S.; 友田 陽*; 齋藤 洋一*; 轟 秀和*; 小貫 祐介*; 鈴木 茂*
鉄と鋼, 104(4), p.201 - 207, 2018/00
To investigate the characteristics of dislocation evolution in ferritic and austenitic stainless steels under tensile deformation, neutron diffraction line-profile analysis was carried out. The austenitic steel exhibited higher work hardening than the ferritic steel. The difference in the work hardening ability between the two steels was explained with the dislocation density estimated by the line-profile analysis. The higher dislocation density of the austenitic steel would originate from its lower stacking fault energy. Dislocation arrangement parameters indicated that the strength of interaction between dislocations in the austenitic steel was stronger than that in the ferritic steel.
中島 健次; 川北 至信; 伊藤 晋一*; 阿部 淳*; 相澤 一也; 青木 裕之; 遠藤 仁*; 藤田 全基*; 舟越 賢一*; Gong, W.*; et al.
Quantum Beam Science (Internet), 1(3), p.9_1 - 9_59, 2017/12
Harjo, S.; 土田 紀之*; 阿部 淳*; Gong, W.*
Scientific Reports (Internet), 7(1), p.15149_1 - 15149_11, 2017/11
Two TRIP-aided multiphase steels with different carbon contents were analyzed in situ during tensile deformation by time-of-flight neutron diffraction to clarify the deformation induced martensitic transformation behavior and its role on the strengthening mechanism. The difference in the carbon content affected mainly the difference in the phase fractions before deformation, where the higher carbon content increased the phase fraction of retained austenite (). However, the changes in the relative fraction of martensitic transformation with respect to the applied strain were found to be similar in both steels since the carbon concentrations in were similar. The stress contribution from martensite was observed increasing during plastic deformation while that from bainitic ferrite hardly changing and that from decreasing.
Harjo, S.; 川崎 卓郎; 諸岡 聡
Advanced Experimental Mechanics, 2, p.112 - 117, 2017/10
To understand strengthening mechanism in lath martensitic steels, in situ neutron diffractions during tensile deformation for 22SiMn2TiB steel and Fe-18Ni alloy were performed using TAKUMI of J-PARC. Profile analyses were performed using Convolutional Multiple Whole Profile (CMWP) fitting and Williamson-Hall (W-H) methods. As results, the dislocation densities as high as 10 m in the as-quenched states of both steels were determined hardly to change or slightly increase by the CMWP method. The reliability of the dislocation density obtained from the W-H method was low, because the whole profile was not considered for the analysis. In the former method, the values of parameter M related to dislocations arrangement was found to decrease rapidly for both steels at the beginning of plastic deformation. Hence, high work hardening in the lath martensitic steels was considered due to the dislocations rearrangements with plastic deformation.
友田 陽*; 関戸 信彰*; 徐 平光; 川崎 卓郎; Harjo, S.; 田中 雅彦*; 篠原 武尚; Su, Y.; 谷山 明*
鉄と鋼, 103(10), p.570 - 578, 2017/10
Various methods were employed to measure the austenite volume fraction in a 1.5Mn-1.5Si-0.2C steel. It has been confirmed that the volume fractions determined by transmission electron microscopy, scanning electron microscopy/electron back scatter diffraction, X-ray diffraction and neutron diffraction exhibit a general trend to become larger in this order, although the values obtained by X-ray and neutron diffraction are similar in the present steel because austenite is relatively stable. The austenite volume fractions determined by diffraction methods have been found to be affected by the measuring specimen direction, i.e., texture, even by applying the conventional correcting procedure. To avoid this influence, it is recommended to measure both of volume fraction and texture simultaneously using neutron diffraction. Although synchrotron X-ray shows higher angle resolution, its small incident beam size brings poor statistic reliability. The influence of texture cannot be avoided for transmission Bragg edge measurement, either, which must be overcome to realize 2D or 3D volume fraction mapping.
Harjo, S.; 川崎 卓郎; 友田 陽*; Gong, W.*; 相澤 一也; Tichy, G.*; Shi, Z.*; Ungar, T.*
Metallurgical and Materials Transactions A, 48(9), p.4080 - 4092, 2017/09
neutron diffraction during tensile deformation of lath martensite steel containing 0.22 mass% of carbon, is performed using TAKUMI of J-PARC. The diffraction peaks at plastically deformed states exhibit asymmetries as the reflection of redistributions of the stress and dislocation densities/arrangements in lath-packets where the dislocation glides are favorable (soft packet) and unfavorable (hard packet). The dislocation density is as high as 10 m at the as-quenched state, and then during tensile straining, the load and the dislocation density become different between the two lath-packets. The dislocation character and arrangement vary also in the hard packet, but hardly change in the soft packet. The hard packet plays an important role in the high work hardening in martensite, which could be understood by taking into account not only the increase of the dislocation density but also the change in dislocation arrangement.
Harjo, S.; 川崎 卓郎; 友田 陽*; Gong, W.
Materials Science Forum, 905, p.46 - 51, 2017/08
To understand the strengthening mechanism of a metallic material with high dislocation density, the plastic deformation behavior of lath martensite was studied by means of in situ neutron diffraction measurements during tensile deformations using a 22SiMn2TiB steel and a Fe-18Ni alloy. The characteristics of dislocation were analyzed and were discussed with the relation of stress-strain curves. The dislocation densities induced by martensitic transformation during heat-treatment in both materials were found to be originally as high as 10 m order, and subsequently to increase slightly by the tensile deformation. The parameter M value which displays the dislocation arrangement dropped drastically at the beginning of plastic deformation in both materials, indicating that the random arrangement became more like a dipole arrangement.
友田 陽*; 佐藤 成男*; Uchida, M.*; 徐 平光; Harjo, S.; Gong, W.; 川崎 卓郎
Materials Science Forum, 905, p.25 - 30, 2017/08
Microstructural change during hot compressive deformation at 700 C followed by isothermal annealing for a Fe-32Ni austnitic alloy was monitored using neutron diffraction. The evolution of deformation texture with 40% compression and its change to recrystallization texture during isothermal annealing were presented by inverse pole figures for the axial and radial directions. The change in dislocation density was tracked using the convolutional muli-profile whole profile fitting method. To obtain the fitting results with good statistics, at least 60 s time-slicing for the event-mode recorded data was needed. The average dislocation density in 60 s after hot compression was determined to be 2.8 10 m that decreased with increasing of annealing time.
土田 紀之*; Nagahisa, N.*; Harjo, S.
Materials Science and Engineering A, 700, p.631 - 636, 2017/07
This study investigated room-temperature creep tests using a low-carbon TRIP steel to clarify the TRIP effect on tensile deformation behavior under constant load. Nominal strain and strain rate increased with an increase in applied stress and those were almost stagnated at holding times of about s. The volume fractions of deformation-induced martensite () at a given true strain obtained from constant load creep tests were larger than those from tensile tests. From the in situ neutron diffraction experiments during the constant load creep tests, the phase strain of the austenite () phase in the creep tests was found to be larger than that in the tensile tests at the same applied stress. This means that the phase strain or true stress of the phase in the TRIP steel was associated with the difference in the volume fraction of between the creep and the tensile tests.