?本報では、予ひずみを付与して原子炉の中性子照射による硬化を模擬した低合金製試験片を対象として、実験室X線を用いた高温その場測定技術（以後、その場測定技術）を活用した熱回復挙動の詳細な観察を行い、熱回復パラメータによる熱回復挙動の推定方法の有用性を改めて確認するとともに、溶接熱サイクルを想定した熱回復挙動の推定方法の高度化について考察する。...
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A Discussion about Thermal Recovery Zone Estimation Based on Lab X-ray In-situ Observation of Thermal Recovery Behavior of Neutron Irradiation-Simulated Materials?

In this study, the effects of seal welding conditions, such as welding heat input, depth of crack, and plate thickness, on the welding-induced residual stress and the stress intensity factor (SIF) around the remaining crack were investigated by finite element analysis. In addition, the parameter Q/√a (Q: welding heat input, a: depth of crack) was theoretically derived from welding thermal conduction theory as representative of the temperature distribution along the crack direction. As the results, it w...
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Study on Welding Procedure Parameter Influencing Structural Soundness at Seal Weld

In nuclear power plants, stress corrosion cracking has been observed near the weld zone of the primary loop recirculation pipes made of low-carbon austenitic stainless steel Type 316L. Residual stress is important factor in the occurrence and propagation of SCC. The joining process of pipes usually includes surface machining and welding, and both processes induce residual stresses. In this study, FEM was used to estimate residual stress distributions generated by butt welding and surface machining. In addi...
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Evaluation of Residual Stress Distribution due to Welding and Surface Machining and Crack Growth Behavior

残留応力と保全（その１　溶接変形と残留応力の基礎）大阪大学 大学院工学研究科望 月 正 人１．はじめに　保全を考えるとき，対象の長期にわたる信頼性を確保するため，初期の製作に配慮するとともに時間経過にともなう保全活動が重要となる．ここで，圧力容器や配管など気密性を要求される構造物の場合，その製作に溶接が用いられることが多いが，直接目には見えない製作時の残留応力が劣化や損傷に影響を及ぼすことに気をつけなければならない．　さて，溶接によって「もの」を「つなぐ」とき，要求通りの形状・寸法を満たすとともに，使......

Abstract Various research projects have been conducted on the residual stress distribution in the pipe weld since it is important to evaluate SCC initiation, or to evaluate structural integrity. Our previous report noted the necessity of considering the influence of complicated residual stresses in multi-path weld joint in order to enhance the evaluation of long-term reliability of mitigated stress. This paper describes the evaluation result about the changes in residual stress caused by variations in...
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Evaluation of varying extent on the residual stress distribution by effect of varied welding application and repair welding

This study is considering the effect of clamp conditions on welding deformation and residual st ress distribution. Welding deformation and residual stress becomes initial imperfections, and i t causes structures weak so it must be controled. The result of numerical analysis shows that an appropriate conditions should be chosen by considering welding distortion and residual stress....
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Effect of condition of clamp on deformation and residual stress in welding

This study shows the effect of the low transformation temperature welding material on residual stress listribution and welding deformation. The expansion due to the transformation fr om austenite to martensite nduces the compressive residual stress around welds. While, in the welding structures, it is important to control the welding deformation and residual stre ss so that they may cause the strength decrease. By using he low temperature transformation welding wire, it may be possible to decrease the weld...
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Numerical simulation of mechanical properities at welding and repairing

１．はじめに　圧力容器や配管など気密性を要求される構造物の場合、その製作に溶接が用いられることが多いが、溶接を行う際の熱エネルギーの影響により材質が変化するだけでなく残留応力や変形が生じる。ここで、直接目には見えない製作時の残留応力が、供用後の劣化や損傷に影響を及ぼすことがあることに気をつけなければならない。時間経過にともなう保全活動においても、時間依存型の損傷に対して残留応力がどのような影響を及ぼすかについて把握しておくことは重要である。さらに、プラント運転後においても諸々の境界条件や荷重レベルが変化す......

Abstract In this study, we focused on the singular weld residual stress distribution could be seen when we evaluated by X-ray dif fraction method. We used specimens welded under two heat input conditions, and so the weld metal of each specimen had a different solidification structure. In the specimen that had martensite in weld, the weld metal showed a clear difference between the resi dual stresses in longitudinal direction and transverse direction. However, in the specimen that had bainitic-ferrit in wel...
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Evaluation of residual stress in weld metal by X-ray diffraction method in consideration of the anisotropy of the X-ray elastic constant

In this study, a fast simulation technique of Iterative Substructure Method (ISM) was applied for numerical analysis of the distribution of residual stress by J-weld and repair weld of Bottom Mounted Instrument (BMI) nozzle in reactor vessel penetration. The calculated results were compared with the measured values to validate the constructed residual stress analysis model. The effect of BMI mounting angles on distribution of residual stress at J-welds was investigated. Based on the results, similarity and...
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Numerical Analysis of Residual Stress by J-weld and Repair Weld of Bottom Mounted Instrument Nozzles in Reactor Vessel Penetration