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Qin, T. Y.*; Hu, F. F.*; 徐 平光; Zhang, R.*; Su, Y. H.; Ao, N.*; Li, Z. W.*; 篠原 武尚; 菖蒲 敬久; Wu, S. C.*
International Journal of Fatigue, 202, p.109233_1 - 109233_16, 2026/01
The surface induction-hardened S38C medium carbon steel shows a good balance of strength and toughness, but complicates the evaluation of fatigue resistance, mainly because of gradient residual stress (RS) and grains. An integrated fatigue resistance assessment (AIFA) framework was proposed to consider the residual stress relief under stochastic loads. To this end, quasi-in situ neutron diffraction and Bragg-edge imaging were combined to probe the evolution of residual stress during crack propagation. Firstly, a rigid-flexible coupled vehicle dynamics model was adopted to obtain the time-domain variable amplitude loading spectrum. Then, Fortran subroutines were developed to assign these data into full-scale S38C axle model, and the remaining life was predicted using the damage tolerance approach. The results demonstrate that crack propagation would accelerate when residual stress is considered in the case of the crack depth exceeding 3.0 mm. It is, for the first time, found that 15 mm- and 5 mm-thickness fan-shaped specimens can retain the axial and hoop residual strain in terms of diffraction angle variation, respectively, for full-scale structural S38C steel axles. In the absence of RS, the remaining life of the axle decreases sharply from 624,800 to 51,300 km as the crack depth increases from 3.0 to 16 mm. Compared with the standard method under constant amplitude loading without residual stress relief, the present AIFA method provides the more accurate but conservative fatigue life prediction.
鈴木 賢治*; 三浦 靖史*; 豊川 秀訓*; 城 鮎美*; 菖蒲 敬久; 諸岡 聡; 柴山 由樹
Quantum Beam Science (Internet), 9(2), p.15_1 - 15_15, 2025/06
In this study, austenitic stainless steel pipes with a small diameter (100A) were butt-welded and the residual stress was measured using high energy synchrotron radiation X-rays and neutron. The welding residual stress is asymmetrical with respect to the welding line and has unevenness due to the crystal grains. Large axial residual stress occurs from the HAZ near the penetration bead toward the weld part. A simulation of a butt-welded pipe was performed using the finite element method. In the half model of the welded pipe, the butt-plane was assumed to keep a plane. The simulated residual stress by the half model was larger than that by the whole model. To perform an accurate simulation, the whole butt-welded piping must be modeled. The real tensile stress area from the HAZ near the penetration bead toward the weld was not obtained by the simulation.
Li, S.; 山口 義仁; 勝山 仁哉; Li, Y.
Proceedings of ASME 2024 Pressure Vessels & Piping Conference (PVP 2024) (Internet), 8 Pages, 2024/07
Flaws due to stress corrosion cracking (SCC) were recently detected in welded joints of austenitic stainless steel piping lines in pressurized water reactors. Welding-induced high hardness and tensile residual stress are known as one of the main factors affecting SCC. In this work, thermal-elastic-plastic coupled three-dimensional finite element analyses were performed to investigate the distributions of welding residual stress and hardness in butt-welded joints of Type 316 stainless steel. Different heat inputs were applied to the pipe welds, including normal heat input, high heat input and very high heat input. Two different constraint conditions were considered for the welded joints, i.e., both ends free or clamped, the latter indicating that the welded joint is constrained by the surrounding piping system. Simulation results were compared with experimental data such as welding thermal cycle, axial shrinkage and residual stress for validation. The effects of heat input and constraint condition on the welding residual stress and hardness at different sections of the welded joints including the weld start/end location were discussed in detail.
Li, S.; 山口 義仁; 勝山 仁哉; Li, Y.; Deng, D.*
Proceedings of ASME 2023 Pressure Vessels and Piping Conference (PVP 2023) (Internet), 7 Pages, 2023/07
In this work, a framework was proposed on the comprehensive assessment of hardness and welding residual stress in Type 316 austenitic stainless steel welded joints. Firstly, an 8-pass butt-welded joint made of Type 316 stainless steel was fabricated. Finite element analysis of the welded joint was performed to investigate hardness and welding residual stress distributions. The grain growth model was developed for the hardness prediction. The Chaboche combined isotropic-kinematic strain hardening model and time-temperature dependent annealing model were adopted. The relationships between the Vickers hardness and the uniaxial plastic strain as well as grain size were collected from published literatures. The simulation results of the grain size and accumulated equivalent plastic strain were used for the hardness prediction of the welded joint. The predicted hardness was compared with the experimental data of hardness mapping. The distribution of welding residual stress on the outer surface of the welded pipe was measured by using the X-ray diffraction method and strain gauge method, respectively. The predicted welding residual stresses were compared with the measurements. The results obtained showed that the developed numerical approach can predict the hardness and welding residual stress of Type 316 stainless steel welded joints with satisfactory accuracy. The effects of structural constraint and heat input on the hardness and welding residual stress will be investigated as further works, as described in the proposed framework.
鈴木 賢治*; 三浦 靖史*; 城 鮎美*; 豊川 秀訓*; 佐治 超爾*; 菖蒲 敬久; 諸岡 聡
材料, 72(4), p.316 - 323, 2023/04
Residual stresses in small-bore butt-welded pipe of austenitic stainless steel have never been measured. It is difficult to obtain a detailed residual stress map of the root welded part, because the gauge volume in neutron diffraction is large. The stress evaluation of the welded part by synchrotron X-rays was also difficult due to the dendritic structure. In this study, a double exposure method (DEM) with high-energy synchrotron X-rays was applied to measuring the details of the residual stress of the welded part, and we succeeded in obtaining the detailed axial and radius stress maps of the root welded part of the plate cut from the welded pipe, though the stress map was under the plane stress condition. The hoop stress map of the butt-welded pipe was obtained using the strain scanning method with neutrons under the triaxial stress state. The axial and radius stress maps under triaxial stress state were made up using the complementary use of the synchrotron X-ray and neutron. As a result, the detailed stress maps of the root welded part of the butt-welded pipe were obtained. The obtained map sufficiently explained the initiation and propagation of SCC.
西田 智*; 西野 創一郎*; 関根 雅彦*; 岡 勇希*; Harjo, S.; 川崎 卓郎; 鈴木 裕士; 森井 幸生*; 石井 慶信*
Materials Transactions, 62(5), p.667 - 674, 2021/05
被引用回数：7 パーセンタイル：35.77(Materials Science, Multidisciplinary)In this study, we used neutron diffraction to analyze in a non-destructive method the distribution of internal residual stress in a free-cutting steel bar processed by cold drawing and straightening. The residual stresses were successfully measured with excellent stress balance. The residual stresses generated by the cold-drawing process were reduced by subsequent straightening, and the distribution of residual stresses by finite element method (FEM) simulation was consistent with the measured values by neutron diffraction. As a result of the FEM analysis, it is assumed that the rod was subjected to strong tensile strains in the axial direction during the drawing process, and the residual stresses were generated when the rod was unloaded. Those residual stresses were presumably reduced by the redistribution of residual stresses in the subsequent straightening process.
鈴木 環輝*; 大川 鉄平*; Harjo, S.; 佐々木 敏彦*
日本機械学会論文集(インターネット), 87(894), p.20-00377_1 - 20-00377_15, 2021/02
The residual stress state inside the cruciform welded joints were measured using the pulsed neutron stress measurement method. The points of interest in this study are the weld toe and its interior. We also compared the cases with and without ultrasonic impact treatment (UIT), which is expected as a fatigue strength improvement technology. Furthermore, the case where tensile stress or compressive stress was applied after UIT treatment was also examined. The applied stresses at this time were 75% or 85% of the yield point, respectively. From the above, we considered the cause of the change in the residual stress on the surface after UIT treatment, which was clarified in the preliminary experiment, in the early stage of fatigue. As a result, the load after the UIT treatment caused plastic deformation in a part of the inside, which caused the redistribution of residual stress.
林 真琴*; 菖蒲 敬久
Residual Stress, p.100 - 132, 2021/00
構造材料は使用中に疲労破壊したり、応力腐食割れを発生することがある。その原因の1つに構造材料の製造過程における熱処理や加工により発生する残留応力がある。その残留応力を測定する手法にはさまざまなものがある。本書では実験室X線や放射光X線、中性子に始まり、超音波や磁気的な手法による測定技術を紹介する。加えて、各種材料における加工や溶接による残留応力の測定例、実機における測定例、残留応力の静的および繰返し荷重による変化挙動、さらにはその変化挙動に基づく疲労余寿命の評価手法などを概説する。
林 眞琴*; 大城戸 忍*; 鈴木 裕士
Quantum Beam Science (Internet), 4(2), p.18_1 - 18_12, 2020/06
In materials with a surface treatment such as shot peening, the residual stress gradient in the surface layer is severe. When measuring the residual stress distribution near the surface with a severe stress gradient by the neutron diffraction method, the gauge volume must be removed from the measurement sample. However, when the gauge volume deviates from the sample, a pseudo peak shift occurs and accurate stress distribution cannot be evaluated. Therefore, it is necessary to evaluate the pseudo peak shift in advance under the same conditions, as in the case of actual residual stress measurement, using a sample in an unstressed state. In this study, the stress distributions in the surface layer of a type 304 stainless steel plate and bar with simulated stress-corrosion cracks which were subjected to water jet peening - giving a surface layer residual stress equivalent better than that of normal shot peening - were evaluated considering the pseudo peak shift. As a result, the residual stress distributions in the surface layer were measured in good agreement with the measurement result obtained by the sequential polishing X-ray diffraction method. It was clarified that the residual stress distribution in the near surface with steep stress gradient can be evaluated by the neutron diffraction method.
Harjo, S.; 川崎 卓郎; Grazzi, F.*; 篠原 武尚; 田中 眞奈子*
Materialia, 7, p.100377_1 - 100377_9, 2019/09
A mapping measurement using pulsed neutron diffraction with time-of-flight method is performed on a full-shape Japanese sword made in Keicho era (1596-1615) to elucidate the manufacturing process. The obtained diffraction patterns are analyzed by the Rietveld refinement and a line profile analysis. The constituent phases in the area closer to the back of the blade (ridge) are found to be ferrite and cementite, composing pearlite, while the area close to the edge is composed by martensite and austenite. The distributions of constituent phases are well explained with the distributions of dislocation density and crystallite size. The carbon contents and the residual macroscopic stresses are estimated from the obtained phase fractions and lattice parameters.
鈴木 賢治*; 菖蒲 敬久
E-Journal of Advanced Maintenance (Internet), 10(4), p.9 - 17, 2019/02
弾性異方性をもつ材料中では、塑性変形が発生した際に結晶間に応力差が生じており、これが材料破壊に深くかかわっていることが知られている。本研究では、高エネルギー放射光回折法を用いて、塑性変形させた材料中の荷重方向の残留応力を結晶方位ごとに調べた。その結果、残留応力はX線的弾性定数(回折面ごとに求められるヤング率)が高い指数では引張残留応力、低い指数では圧縮残留応力が発生していることがわかった。この結果は、材料強度を向上させる際、集合組織のように結晶方位を制御する技術に役立つと考えている。
生島 一樹*; 木谷 悠二*; 柴原 正和*; 西川 聡*; 古川 敬*; 秋田 貢一; 鈴木 裕士; 諸岡 聡
溶接学会論文集(インターネット), 35(2), p.75s - 79s, 2017/06
In this research, to investigate the effect of shot peening on operation, an analysis method to predict the behavior of stress distribution on shot peening was proposed. In the proposed system, the load distribution on the collision of shots was modeled, and it was integrated with the dynamic analysis method based on the Idealized explicit FEM (IEFEM). The thermal elastic plastic analysis method using IEFEM was applied to the analysis of residual stress distribution of multi-pass welded pipe joint. The computed residual stress distribution was compared with the measured residual stress distribution using X-ray diffraction (XRD). As a result, it was shown that the both welding residual stress distribution agree well with each other. Considering the computed welding residual stress distribution, the modification of stress distribution due to shot peening was predicted by the proposed analysis system.
秋田 貢一; 柴原 正和*; 生島 一樹*; 西川 聡*; 古川 敬*; 鈴木 裕士; Harjo, S.; 川崎 卓郎; Vladimir, L.*
溶接学会論文集(インターネット), 35(2), p.112s - 116s, 2017/06
Residual stresses near the weld metal of the joints before and after a thermal cycle were measured using a reactor based neutron diffraction technique in room temperature. In-situ residual stress measurements were performed on the plate type sample using a pulsed neutron diffraction technique under thermal cycles. Residual stress behaviors of the samples were examined also by the idealized explicit FEM (IEFEM), which agreed well with the experimental results of the residual stress behaviors during thermal cycles. Thermal stresses were induced near the weld metal by the difference of the linear expansion coefficients of the dissimilar base metals. Since the thermal stress exceeded the yield stress of the material during the first heating process, the residual stresses near the weld metal were redistributed and a part of the residual stress was relaxed.
鈴木 裕士
熱処理, 46(1), p.11 - 18, 2006/02
X線回折法による非破壊応力測定技術は、ひずみゲージなどの機械的計測法に代わる測定技術として、工業分野から研究開発分野に至るまで、さまざまな分野に応用されている。最近では、放射光から得られる高エネルギーX線や中性子線を用いた新しい応力測定技術が開発され、材料表面直下や材料深部など、実験室系では測定が困難であった領域・条件における残留応力評価が可能になっている。本解説では、これら特性X線,高エネルギーX線,中性子線による残留応力測定技術について、その基本原理と幾つかの応用例について解説した。
柴田 勝之*; 鬼沢 邦雄; 鈴木 雅秀; Li, Y.*
日本機械学会M&M2005材料力学カンファレンス講演論文集, p.299 - 300, 2005/11
改正電気事業法及び改正省令62号等が平成15年から施行され、構造機器の健全性に影響しない欠陥を残したまま運転継続が可能な維持基準が適用されている。運転継続にあたっては、欠陥の進展評価と健全性確認を行うことが必要である。応力腐食割れ等の進展には溶接残留応力が大きく影響するので残留応力の影響評価が重要である。現行規格では、影響関数により求めた応力拡大係数(K値)を用いて残留応力の影響を評価しているが、き裂進展とともに残留応力が解放されき裂先端には塑性域が生じるので、残留応力を荷重制御型の荷重として扱う影響関数法で求めたK値による進展解析が最適かどうかは疑問である。そこで、残留応力中をき裂が進展するときの残留応力の挙動を弾塑性解析し、残留応力の再分布の様子やき裂進展とK値との関係を求め、影響関数法によるK値と比較した。数種類の溶接残留応力中におけるき裂進展シミュレーションを行い残留応力の再分布及びK値の解析結果から、モデル長さの影響,端部拘束条件の影響,き裂先端部の塑性変形の影響を検討し、影響関数法によるK値を裂進展解析に適用した場合はき裂進展を過大評価することを明らかにした。
鈴木 裕士; Holden, T. M.*; 盛合 敦; 皆川 宣明*; 森井 幸生
材料, 54(7), p.685 - 691, 2005/07
本研究では、高張力鋼の一つであるNi-Cr鋼を用いて製作したX開先突合せ溶接試験片の残留応力分布を中性子回折法により測定し、残留応力発生メカニズムを検討した。始めに、無ひずみ状態における格子定数を測定するために、溶接試験片から幾つかの小片試料を切り出した。小片試料を用いて格子定数を測定した結果、溶接過程において生じたマルテンサイト変態などの相変態が影響して、溶接部近傍で格子定数の増加が認められた。次に、
Fe110, Fe200, Fe211の三種類の回折により溶接試験片の残留応力分布を測定した。塑性ひずみの影響が無いために、それぞれの回折により評価した残留応力分布はほとんど同様な傾向を示していた。また、溶接部近傍における残留応力はNi-Cr鋼の降伏強さの半分程度の引張残留応力であった。高張力鋼では軟鋼と比べて相変態による膨張量が大きいこと、また、引張残留応力がかなり低い温度となってから発生し始めるために、残留応力が降伏応力に至らなかったと考えられる。したがって、高張力鋼の中性子応力評価では、塑性ひずみの発生を考慮する必要の無いことを確認した。
鈴木 裕士; 盛合 敦; 皆川 宣明*; 森井 幸生
材料, 54(3), p.339 - 345, 2005/03
中性子応力測定の従来法では、格子ひずみを計算するために、無ひずみ状態の格子定数を正確に把握する必要がある。著者らは、粉末や焼なまし試料などの標準試料を用いて測定した格子定数を用いることなく、三軸残留応力を評価できる中性子応力測定法を開発した。本研究では、この提案した方法を用いて溶接材の残留応力分布を測定した。まず始めに、溶接材料から切り出した小片試料を用いて、溶接材料の格子定数分布を測定した。その結果、HAZ部(熱影響部)に生じたマルテンサイト変態のために、溶接部近傍において格子定数が大きくなる傾向が確認された。提案した方法により評価した格子定数分布もまた、溶接部近傍において大きくなる傾向を示し、また、格子定数の絶対値は、小片試料のそれとほとんど同じであった。したがって、格子定数の分布が存在するような材料であっても、提案した方法を用いることで、格子定数を推定できると考えられる。従来法及び提案した方法により残留応力分布を評価した。その結果、提案した方法により決定した残留応力分布は、従来法により求めた残留応力分布とほとんど同じであった。したがって、提案した方法は、複雑な残留応力状態を有する材料においても、残留応力分布を正確に決定できると考えられる。
鈴木 裕士; 皆川 宣明*; 盛合 敦; 旗谷 充彦*; 森井 幸生
Materials Science Forum, 490-491, p.245 - 250, 2005/00
中性子回折を用いた応力測定法は、直交する三方向の格子ひずみを測定することにより応力状態を決定する。従来法では、全ての三方向において同型面の格子ひずみを測定する必要がある。しかしながら、集合組織を有する材料においては、全ての方向において同型面の格子ひずみを測定することが困難であったり、試料の大きさや形状により、三方向全ての格子ひずみを測定することができない可能性がある。さらに、従来の残留応力の測定では、無ひずみ状態の格子面間隔d
が必要不可欠なため、応力測定精度は、粉末試料や焼なまし試料を用いて測定した無ひずみ状態の格子面間隔dの正確さに依存した。そこで、本研究では、これらの問題点を解決することを目的とし、三方向全てにおいて同型面でなくても、二方向あるいは三方向における格子ひずみを測定することにより残留応力状態を決定できる高汎用性の応力測定法を提案し、また、無ひずみ状態の格子面間隔がわからなくとも内部残留応力を決定できる応力測定法についても提案した。
本橋 嘉信*; 柴田 大受; Harjo, S.*; 佐久間 隆昭*; 石原 正博; 馬場 信一; 沢 和弘
Proceedings of 14th International Federation for Heat Treatment and Surface Engineering Congress Transactions of Materials and Heat Treatment Vol.25 No.5, p.1032 - 1036, 2004/10
高温で超塑性特性を示す3Y-TZP(3mol%イットリア含有正方晶ジルコニア多結晶体)に、日本原子力研究所東海研究所のTANDEM加速器を用いて+11価,130MeVのZrイオンを照射した。照射によるはじき出し損傷はTRIMコードにより解析し、照射による機械的特性及び破壊様式の変化,その後の焼き鈍しの影響,微小硬度計の押込み深さと照射表面からの深さとの関係について検討を行った。その結果、照射直後の試験片では、表面に圧縮応力が生じ、硬さと破壊靭性の増加が観察された。また、その後の焼き鈍しでは温度の増加に伴いこれらの変化が徐々に緩和した。これらの原因としては、照射により粒界間の結合力が弱められたためであると考えられる。
O
接合体の高温曲げ特性佐藤 隆史*; 本橋 嘉信*; 佐久間 隆昭*; 早稲田 一嘉*; 柴田 大受; 石原 正博; 沢 和弘
日本機械学会関東支部茨城講演会(2004)講演論文集(No.040-3), p.55 - 56, 2004/09
将来の高温ガス炉への応用が期待されている超塑性3Y-TZP(3mol%イットリア含有正方晶ジルコニア多結晶体)について、3Y-TZPを接合材としてアルミナを接合させ、その後4点曲げ試験を実施し、接合特性として以下の結論を得た。(1)曲げ温度が接合温度に近づくと残留応力を緩和して曲げ強度が上昇する。(2)高温での接合体の強度は、3Y-TZPの強度及び接合界面の気孔状態に依存する。(3)超塑性3Y-TZPを用いることで、金属材料を用いて接合した場合より優れた強度特性が得られた。
