In this study, a predictive simulation model coupling weld bead formation and thermal conduction was developed for construction of the method of predicting or evaluating the temperature distribution during temper bead welding. Welding parameters used in the analysis were estimated from experimental welding conditions based on the thermal conduction theory and numerical simulations of previous works. The simulation results were compared with the experimental results under the same welding conditions to ...
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Predictive Simulation Model of Bead Shape and Temperature Distribution during Temper Bead Welding

Weld residual stress and distortion affect to fatigue, SCC, static tensile strength, brittle fracture, or other failures in various components. Computational method is useful for evaluating weld residual stress and distortion as well as direct measuring method. Re cently developed methods by the authors for innovative numerical simulation of weld residual stress in various scales and fields are introduced. A lot of applications of the computational approach to weld residual stress evaluation are expected ...
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Innovative Computational Simulation of Weld Residual Stress from Mega- to Micro-Structures

Hamaoka nuclear power plant unit-5 had the sea water intrusion incident in 2011 during the shut-down process. We, Chubu electric power company, have conducted some researches for unit-5 re-start, since we had some concerns about the aftercare of pitting corrosions occurred in the inner surface of RPV. The aftercare includes the determination of whether corrosion pitting might propagate until RPV, determination of whether or not to clean Chloride ions in corrosion pits and the determination of need for weld ...
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Weld repair of sea water induced corrosion pits in inner RPV surface

In this study, a semi-nondestructive procedure for stress strain curve estimation was developed using instrumented indentation technique. Additionally, to estimate local stress ? strain curve in the welds with mechanical heterogeneity, a relation between spherical indentation size and measuring range of mechanical property was quantified by using finite element analysis of spherical indentation technique. The developed technique was applied to estimate mechanical properties of low alloy steel and its weld...
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Study on Mechanical Characterization of Steel and Its Welds through Instrumented Indentation Technique

The Deep hole drilling (DHD) technique has received much attention as a measurement method for through-thickness residual stress. In the past, however, the traditional DHD technique has ignored the effects of plastic deformation around a reference hole, which has been occurred in the DHD procedure. Therefore, the evaluation results obtained by the traditional DHD technique can have accuracy problem. When residual stress is large, the problem is serious because the area which deform plastically. In this...
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A highly accurate residual stress measurement method by the deep hole drilling technique considering the effect of plastic deformation

In order to reutilize nuclear power generation and maintain their presence, it is important to take actions based on assumptions beyond "safety myth". For example, in the field of SCC, long term reliability may be further assured based on evaluation under severer condition than the usual operating environment. Since such severe conditions cannot be reasonably simulated by the experiment in the laboratory, it is effective to utilize numerical simulation as reported in the previous paper. This paper rep...
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Development of an evaluation method utilizing numerical simulation to assure long-term reliability of residual stress improvement by surface treatment

?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

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