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伊東 達矢; 小川 祐平*; Gong, W.; Mao, W.*; 川崎 卓郎; 岡田 和歩*; 柴田 曉伸*; Harjo, S.
Acta Materialia, 287, p.120767_1 - 120767_16, 2025/04
Incorporating solute hydrogen into Fe-Cr-Ni-based austenitic stainless steels enhances both strength and ductility, providing a promising solution to hydrogen embrittlement by causing solid-solution strengthening and assisting deformation twinning. However, its impacts on the relevant lattice defects evolution (, dislocations, stacking faults, and twins) during deformation remains unclear. This study compared the tensile deformation behavior in an Fe-24Cr-19Ni (mass%) austenitic steel with 7600 atom ppm hydrogen-charged (H-charged) and without hydrogen-charged (non-charged) using
neutron diffraction. Hydrogen effects on the lattice expansion, solid-solution strengthening, stacking fault probability, stacking fault energy, dislocation density, and strain/stress for twin evolution were quantitatively evaluated to link them with the macroscale mechanical properties. The H-charged sample showed improvements in yield stress, flow stress, and uniform elongation, consistent with earlier findings. However, solute hydrogen exhibited minimal influences on the evolution of dislocation and stacking fault. This fact contradicts the previous reports on hydrogen-enhanced dislocation and stacking fault evolutions, the latter of which can be responsible for the enhancement of twinning. The strain for twin evolution was smaller in the H-charged sample compared to the non-charged one. Nevertheless, when evaluated as the onset stress for twin evolution, there was minimal change between the two samples. These findings suggest that the increase in flow stress due to the solid-solution strengthening by hydrogen is a root cause of accelerated deformation twinning at a smaller strain, leading to an enhanced work-hardening rate and improved uniform elongation.
伊東 達矢; 小川 祐平*; Gong, W.; Mao, W.*; 川崎 卓郎; 岡田 和歩*; 柴田 曉伸*; Harjo, S.
Proceedings of the 7th International Symposium on Steel Science (ISSS 2024), p.237 - 240, 2024/11
Hydrogen embrittlement has long been an obstacle to the development of safe infrastructure. However, in contrast to hydrogen's embrittling effect, recent research has revealed that the addition of hydrogen improves both the strength and uniform elongation of AISI Type 310S austenitic stainless steel. A detailed understanding of how hydrogen affects the deformation mechanism of this steel could pave the way for the development of more advanced materials with superior properties. In the present study, neutron diffraction experiments were conducted on Type 310S steel with and without hydrogen-charged to investigate the effect of hydrogen on the deformation mechanism. In addition to the effect of solid-solution strengthening by hydrogen, the q-value, a parameter representing the proportion of edge and screw dislocations in the accumulated dislocations, was quantitatively evaluated using CMWP analysis on neutron diffraction patterns. The comparison of q-values between the hydrogen-charged and non-charged samples reveals that hydrogen has minimal effect on dislocation character in Type 310S steel.
上路 林太郎*; Gong, W.; Harjo, S.; 川崎 卓郎; 柴田 曉伸*; 木村 勇次*; 井上 忠信*; 土田 紀之*
ISIJ International, 64(2), p.459 - 465, 2024/01
被引用回数:0 パーセンタイル:0.00(Metallurgy & Metallurgical Engineering)Deformation-induced martensitic transformation (DIMT) during tensile or compressive deformations of the bainitic steels with various carbon content (0.15%C, 0.25%C, 0.62%C) was studied. In all of the bainitic steels, the tensile deformation exhibited larger work hardening than the compression. This difference indicates the suppression of the DIMT at the compression, and actually the measurements of electron back scattering diffraction (EBSD) confirmed the less reduction of retained austenite at the compression of all the bainitic steels. Additionally, the steel with the highest carbon content was examined by in situ neutron diffraction and clarified the difference similar to that obtained by the EBSD measurement. The regression of the relation between the fraction of austenite and applied strain with the conventional empirical equation revealed that the kinetic of DIMT is strongly dependent with the stress polarity, but not significantly changed by the carbon content.
Mao, W.; Gao, S.*; Gong, W.; Bai, Y.*; Harjo, S.; Park, M.-H.*; 柴田 曉伸*; 辻 伸泰*
Acta Materialia, 256, p.119139_1 - 119139_16, 2023/09
被引用回数:24 パーセンタイル:97.11(Materials Science, Multidisciplinary)変形誘起塑性(TRIP)鋼は、変形誘起マルテンサイト変態(DIMT)に伴う加工硬化率の向上により、強度と延性の優れた組み合わせを示す。TRIP鋼や合金の加工硬化挙動におけるDIMTの役割を定量的に評価することは、強度と延性の両立を可能にする先進材料を設計するための指針を与えるが、変形中に相組成が変化し続け、応力と塑性ひずみの両方が構成相間で動的に分配されるため、その評価は困難である。本研究では、Fe-24Ni-0.3C(wt.%)TRIPオーステナイト鋼の引張変形とその場中性子回折測定を行った。中性子回折測定による応力分割と相分割に基づく解析手法を提案し、試験片の引張流動応力と加工硬化率を、オーステナイト母相,変形誘起マルテンサイト、DIMT変態速度に関連する因子に分解し、試料の加工硬化挙動における各因子の役割を考察した。さらに、回折プロファイル解析により測定した転位密度を用いてオーステナイトとマルテンサイト間の塑性ひずみ分配を間接的に推定し、材料中のオーステナイトとマルテンサイト間の応力・ひずみ分配の全体像を構築した。その結果、変形誘起マルテンサイト変態速度とマルテンサイトが負担する相応力の両方が、材料の全体的な引張特性に重要な役割を果たしていることが示唆された。提案した分解解析法は、TRIP現象を示す多相合金の機械的挙動を調べるために広く適用できる可能性がある。
Gong, W.; Harjo, S.; 友田 陽*; 諸岡 聡; 川崎 卓郎; 柴田 曉伸*; 辻 伸泰*
Acta Materialia, 250, p.118860_1 - 118860_16, 2023/05
被引用回数:14 パーセンタイル:93.49(Materials Science, Multidisciplinary)Martensitic transformation is accompanied by the generation of microscale and macroscale internal stresses during cooling below the martensitic transformation start temperature. These internal stresses have been determined through X-ray or neutron diffraction, but the reported results are not consistent, probably because the measured lattice parameter is influenced not only by the internal stress but also by several factors, including solute elements and crystal defects. Therefore, neutron diffraction combined with dilatometry measurements during martensitic transformation and subsequent cyclic tempering were performed for an Fe-18Ni alloy. The phase strains calculated by lattice parameter variations show that a hydrostatic compressive strain in austenite and a tensile strain in martensite arose as the martensitic transformation progressed during continuous cooling or isothermal holding. However, the phase stresses of austenite and martensite estimated from these strains failed to hold stress balance law when dense crystal defects involved in the processes. After these crystal defects were removed by appropriate tempering, the stress balance law held well. Meanwhile, the phase stresses of austenite and martensite were changed to opposite, revealing their true identity. Various crystal defects in austenite and martensite, introduced by plastic accommodation, were suggested to affect their lattice parameters and then their phase stresses.
Guo, B.*; Mao, W.; Chong, Y.*; 柴田 曉伸*; Harjo, S.; Gong, W.; Chen, H.*; Jonas, J. J.*; 辻 伸泰*
Acta Materialia, 242, p.118427_1 - 118427_11, 2023/01
被引用回数:11 パーセンタイル:73.00(Materials Science, Multidisciplinary)Dynamic transformation from alpha (HCP) to beta (BCC) phase in a zirconium alloy was revealed by the use of in-situ neutron diffraction during hot compression. The dynamic transformation was unexpectedly detected during isothermal compression at temperatures of 900C and 950
C (alpha + beta two-phase region) and strain rates of 0.01 s
and 0.001 s
, even though equilibrium two-phase states were achieved prior to the hot compression. Dynamic transformation was accompanied by diffusion of Sn from beta to alpha phase, which resulted in changes of lattice parameters and a characteristic microstructure of alpha grains. The details of dynamic transformation are discussed using the evolution of lattice constants.
芝田 悟朗; Won, C.*; Kim, J.*; 野中 洋亮*; 池田 啓祐*; Wan, Y.*; 鈴木 雅弘*; 小出 常晴*; 田中 新*; Cheong, S.-W.*; et al.
Photon Factory Activity Report 2022 (インターネット), 2 Pages, 2023/00
Feをインターカレートした遷移金属ダイカルコゲナイド化合物FeTiS
およびFe
TaS
は、巨大な保磁力および垂直磁気異方性を示す強磁性体になることが知られている。我々は以前、Fe
TiS
についてのX線磁気円二色性(XMCD)実験の結果から、Fe
の凍結していない軌道磁気モーメントが結晶場の1次摂動によって直接磁気異方性エネルギーを生むことを明らかにした。今回、Fe
TiS
よりもさらに強い磁気異方性を示す遷移金属ダイカルコゲナイドFe
TaS
について同様にXMCD実験を行い、磁気異方性の強さが何によって左右されているかを探ることを試みた。
Shaimerdenov, A.*; Gizatulin, S.*; Dyussambayev, D.*; Askerbekov, S.*; 植田 祥平; 相原 純; 柴田 大受; 坂場 成昭
Nuclear Engineering and Technology, 54(8), p.2792 - 2800, 2022/08
被引用回数:8 パーセンタイル:79.63(Nuclear Science & Technology)In the core of the WWR-K reactor, a long-term irradiation of tri-structural isotopic (TRISO)-coated fuel particles (CFPs) with a UO kernel was carried out under normal operating conditions of the high-temperature gas-cooled reactor (HTGR). This TRISO fuel was attained at the temperature of 950 to 1,100
C, and the uranium burnup of 9.9% FIMA (fission per initial metal atom) during the irradiation. The release of the gaseous fission product from the fuel was measured in-pile, and its release-to-birth (R/B) ratio was evaluated using the model developed in the High-Temperature Engineering Test Reactor (HTTR) project. After the irradiation test, fuel compacts were subjected to electric dissociation and nondestructive inspections such as X-ray radiography and gamma spectrometry. Finally, it was concluded that integrity of the TRISO fuel irradiated at approximately 9.9% FIMA was demonstrated, and a low fuel failure fraction and a low R/B measured with krypton-88 indicated good performance and reliability of the high burnup TRISO fuel.
久保 重信; Payot, F.*; 山野 秀将; Bertrand, F.*; Bachrata, A.*; Saas, L.*; Journeau, C.*; Gosse, S.*; Quaini, A.*; 柴田 明裕*; et al.
Proceedings of International Conference on Fast Reactors and Related Fuel Cycles; Sustainable Clean Energy for the Future (FR22) (Internet), 8 Pages, 2022/04
The paper presents major outcomes of the France-Japan ASTRID collaboration and the work program from 2020 to 2024 in the field of severe accident study. In the ASTRID collaboration, severe accident sequences were summarized based on the various safety analyses for the important accident phases, which contributed to strengthen the confidence in the ASTRID severe accident progression for a robust safety demonstration and identification of R and D programs of common interest. Collaborative analysis has been conducted to evaluate ASTRID mitigation device efficiency for mitigation of power excursions, material relocation, debris bed and molten pool behavior on the core catcher. The methodology for mechanical consequence assessment was also developed. In order to support the reactor studies, experimental studies have been planned and conducted regarding the reaction of core material mixtures, in-pile experiments for the fuel pin failure and material relocation through a steel duct structure, and out-of-pile experiments for the fuel coolant interaction (FCI) in the sodium pool. Severe accident analysis tool SIMMER-V with new simulation capabilities and SEASON platform have also been developed. Based on these successful achievements, several tasks to study the large fields of the severe accident domain, which include development of severe accident analysis methodologies and synthesis of SA sequences and consequences, thermodynamics, kinetic and thermo-physical studies of core material mixture, development and validation of SIMMER-V, experimental programs on the molten core material relocation and FCI. After defining the technical contents and implementation plans, the five years study programs have been started.
Mao, W.; Gao, S.*; Bai, Y.*; Park, M.-H.*; 柴田 曉伸*; 辻 伸泰*
Journal of Materials Research and Technology, 17, p.2690 - 2700, 2022/03
被引用回数:16 パーセンタイル:84.42(Materials Science, Multidisciplinary)超微細結晶粒(UFG)組織を有する準安定オーステナイト鋼は、冷間圧延中の変形誘起マルテンサイト変態と焼鈍時のオーステナイトへの逆変態を利用することにより、従来の冷間圧延および焼鈍プロセスで製造することができる。しかし、変形誘起マルテンサイト変態に対するオーステナイトの機械的安定性が高い場合には、冷間圧延中に十分な量のマルテンサイトが生成しないため、このようなプロセスは適用できない。本研究では、高い機械的安定性を有するFe-24Ni-0.3C準安定オーステナイト鋼に対して、冷間圧延と焼鈍の2段階プロセスを適用した。冷間圧延に先立ち、繰り返しサブゼロ処理と逆焼鈍処理を施した。このような処理により、オーステナイトの機械的安定性が劇的に低下し、その後の冷間圧延工程で変形誘起マルテンサイトの生成が大幅に促進された。その結果、結晶粒の微細化が著しく促進され、平均オーステナイト粒径0.5mmの完全再結晶試験片の作製に成功し、高強度と高延性を両立させた。
Lavakumar, A.*; Park, M. H.*; Gao, S.*; 柴田 曉伸*; 興津 貴隆*; Gong, W.; Harjo, S.; 辻 伸泰*
IOP Conference Series; Materials Science and Engineering, 580, p.012036_1 - 012036_6, 2019/09
被引用回数:3 パーセンタイル:80.63(Engineering, Mechanical)Multi-phase steels showing transformation induced plasticity (TRIP), can exhibit an excellent combination of high strength and good ductility by the aid of martensitic transformation during deformation. Even though TRIP-assisted multi-phase steels have been widely used in industry, the role of each phase in the enhancement of mechanical properties is still unclear given their complicated microstructures. In order to understand better the nature of the TRIP effect, the mechanical interaction between different phases at the micro-scale should be clarified. In the present study, the mechanical behavior of a transformation induced plasticity (TRIP) assisted multi-phase steel, has been characterized by neutron diffraction during tensile testing. The result of strain partitioning between the different phases obtained from the
neutron analysis revealed that the martensite phase took much more elastic strain than the ferrite and retained austenite phases, which suggests that the work hardening behavior in the present steel is affected by the higher load borne by deformation-induced martensite.
柴田 曉伸*; 竹田 泰成*; Park, N.*; Zhao, L.*; Harjo, S.; 川崎 卓郎; Gong, W.*; 辻 伸泰*
Scripta Materialia, 165, p.44 - 49, 2019/05
被引用回数:34 パーセンタイル:85.06(Nanoscience & Nanotechnology)Nowadays, a new concept of process utilizing dynamic ferrite transformation, which can achieve ultrafine-grained structure with a mean grain size of approximately 1m, has been proposed. This paper reports transformation mode of dynamic ferrite transformation and formation mechanism of ultrafine-grained structure revealed by our novel technique of
neutron diffraction analysis during thermomechanical processing. Dynamic ferrite transformation occurs in a diffusional manner, whose partitioning behavior changes from para- to ortho-equilibrium with the progress of transformation. Moreover, we propose that dynamic recrystallization of dynamically-transformed ferrite is the main mechanism for the formation of ultrafine-grained structure.
Shaimerdenov, A.*; Gizatulin, S.*; Kenzhin, Y.*; Dyussambayev, D.*; 植田 祥平; 相原 純; 柴田 大受
Proceedings of 9th International Topical Meeting on High Temperature Reactor Technology (HTR 2018) (USB Flash Drive), 6 Pages, 2018/10
高温ガス炉燃料の100GWd/tへの高燃焼度化開発のため、原子力機構の協力の下、国際科学技術センター(ISTC)のプロジェクトにおいて、カザフスタン核物理研究所(INP)が高温ガス炉燃料試料の照射試験並びに照射後試験を実施している。新設計の四層三重(TRISO)被覆燃料粒子を円筒状の黒鉛マトリックス燃料コンパクトに成形した照射燃料試料は、日本において製作された。ヘリウムガススウィープ照射キャプセルの設計製作はINPが実施し、WWR-K照射炉を用いての照射試験が2015年4月から実施された。次の段階として、照射済み燃料試料の照射後試験が2017年2月にISTCの新規プロジェクトとして開始された。照射済み燃料試料の非破壊試験および破壊試験に係る様々な照射後試験技術がINPによって開発された。本報では、高燃焼度化TRISO燃料の照射後試験のために開発した技術並びに試験結果について中間報告する。
柴田 大受; 水田 直紀; 角田 淳弥; 坂場 成昭; 大崎 貴士*; 加藤 秀樹*; 井澤 祥一*; 武藤 剛範*; Gizatulin, S.*; Shaimerdenov, A.*; et al.
Proceedings of 9th International Topical Meeting on High Temperature Reactor Technology (HTR 2018) (USB Flash Drive), 7 Pages, 2018/10
高温ガス炉(HTGR)の炉内構造物には黒鉛が用いられている。空気侵入事故による黒鉛構造物の酸化は、安全性の観点から重要な課題である。黒鉛表面へのSiC被覆は、黒鉛の耐酸性を向上させる有望な技術である。しかし、炉内構造物への適用については、この材料の高温、中性子照射に対する健全性を確認することが重要である。原子力機構と日本の黒鉛メーカは耐酸化黒鉛の研究開発を進めてきた。原子力機構とカザフスタンINPとは、ISTCパートナープロジェクトの枠組みを利用して耐酸化黒鉛に対する中性子照射効果について調べた。本報は、SiC被覆を施した耐酸化黒鉛への中性子照射後試験の結果について述べるものである。耐酸化黒鉛のうち、ある一つの銘柄については照射後の酸化試験において優れた特性を示した。
水田 直紀; 角田 淳弥; 柴田 大受; 大崎 貴士*; 加藤 秀樹*; 井澤 祥一*; 武藤 剛範*; Gizatulin, S.*; 坂場 成昭
炭素材料科学の進展; 日本学術振興会第117委員会七十周年記念誌, p.161 - 166, 2018/10
原子力機構及び日本の黒鉛メーカ4社(東洋炭素,イビデン,東海カーボン,新日本テクノカーボン)は、高温ガス炉の炉内構造材料に用いる黒鉛の耐酸化性を向上させることを目的に、CVD法によりSiCコーティングを施した耐酸化黒鉛の研究を進めている。本報では、国際科学技術センター(ISTC)のパートナープロジェクトとして実施した、カザフスタン共和国の核物理研究所(INP)のWWR-K炉による耐酸化黒鉛の中性子照射試験について紹介する。照射試験に先立ち、各試験片に対して未照射条件での酸化試験を行った結果、耐酸化試験片全てにおいて、CVD法により施されたSiCコーティングが十分な耐酸化性を示すことがわかった。中性子照射試験は終了しており、今後はWWR-Kホットラボでの炉外酸化試験を行う計画である。
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 700
C and reached the equilibrium state during subsequent isothermal holding for around 3 ks.
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
J-PARC物質・生命科学実験施設の中性子実験装置についてのレビューである。物質・生命科学実験施設には23の中性子ビームポートがあり21台の装置が設置されている。それらは、J-PARCの高性能な中性子源と最新の技術を組み合わせた世界屈指の実験装置群である。このレビューでは、装置性能や典型的な成果等について概観する。
Jungclaus, A.*; Grawe, H.*; 西村 俊二*; Doornenbal, P.*; Lorusso, G.*; Simpson, G. S.*; Sderstr
m, P.-A.*; 炭竃 聡之*; Taprogge, J.*; Xu, Z. Y.*; et al.
Physics Letters B, 772, p.483 - 488, 2017/09
被引用回数:8 パーセンタイル:52.76(Astronomy & Astrophysics)A new high-spin isomer in the neutron-rich nucleus Cd was populated in the projectile fission of a
U beam at the Radioactive Isotope Beam Factory at RIKEN. A half-life of T
= 6.3(8) ms was measured for the new state which was tentatively assigned a spin/parity of (15
). The isomeric state decays via the emission of a 309-keV
ray with
multipolarity. The experimental results are compared to shell model calculations performed using state-of-the-art realistic effective interactions and to the neighbouring nucleus
Cd. The comparison with calculations shows that adjustments of the pairing and multipole parts of the effective interaction derived from the CD-Bonn nucleon-nucleon potential are required in order to describe the properties of nuclei in the region around
Sn.
Li, B.; 川北 至信; Liu, Y.*; Wang, M.*; 松浦 直人*; 柴田 薫; 河村 聖子; 山田 武*; Lin, S.*; 中島 健次; et al.
Nature Communications (Internet), 8, p.16086_1 - 16086_9, 2017/06
被引用回数:81 パーセンタイル:90.56(Multidisciplinary Sciences)Perovskite CHNH
PbI
exhibits outstanding photovoltaic performances, but the understanding of the atomic motions remains inadequate even though they take a fundamental role in transport properties. Here, we present a complete atomic dynamic picture consisting of molecular jumping rotational modes and phonons, which is established by carrying out high-resolution time-of-flight quasi-elastic and inelastic neutron scattering measurements in a wide energy window ranging from 0.0036 to 54 meV on a large single crystal sample, respectively. The ultrafast orientational disorder of molecular dipoles, activated at approximately 165 K, acts as an additional scattering source for optical phonons as well as for charge carriers. It is revealed that acoustic phonons dominate the thermal transport, rather than optical phonons due to sub-picosecond lifetimes. These microscopic insights provide a solid standing point, on which perovskite solar cells can be understood more accurately and their performances are perhaps further optimized.
柴田 大受; 角田 淳弥; 坂場 成昭; 大崎 貴士*; 加藤 秀樹*; 井澤 祥一*; 武藤 剛範*; Gizatulin, S.*; Shaimerdenov, A.*; Dyussambayev, D.*; et al.
Proceedings of 8th International Topical Meeting on High Temperature Reactor Technology (HTR 2016) (CD-ROM), p.567 - 571, 2016/11
高温ガス炉(HTGR)に用いられている黒鉛について、さらなる安全裕度を確保するため、耐酸化性を向上させることが望ましい。黒鉛表面へのSiC被覆は、そのための候補技術である。原子力機構と日本の黒鉛メーカ4社:東洋炭素,イビデン,東海カーボン,新日本テクノカーボンとで、耐酸化黒鉛を炉内黒鉛構造物に適用する研究を進めている。国際科学技術センター(ISTC)のパートナープロジェクトとして、カザフスタン共和国の核物理研究所(INP)のWWR-K炉により、照射キャプセル2体により耐酸化黒鉛に対する中性子照射試験を実施した。WWR-K炉で、照射温度1473Kにおける10サイクル200日間の照射試験を完了した。最大の高速中性子(E0.18MeV)照射量は、中央の照射孔に装荷したキャプセルで1.2
10
/m
、炉側部の照射孔に装荷したキャプセルで4.2
10
/m
であった。照射後の試験片について、寸法、重量測定、光学顕微鏡による外観観察を実施した。今後、炉外での酸化試験を行う計画である。