表面加工による残留応力改善の長期信頼性評価について


英字タイトル:
Prediction method of long-term reliability in improving residual stresses by means of surface finishing
著者:
瀬良 健彦 Takehiko SERA 平野 伸朗 Shinro HIRANO 千種 直樹 Naoki CHIGUSA 岡野 成威 Shigetaka OKANO 才田 一幸 Kazuyoshi SAIDA 望月 正人 Masahito MOCHIZUKI 西本 和俊 Kazutoshi NISHIMOTO
発刊日:
公開日:
カテゴリ: 論文
キーワードタグ:

概要

Abstract Surface finishing methods, such as Water Jet Peening (WJP), have been applied to welds in some major components of nuclear power plants as a counter measure to Primary Water Stress Corrosion Cracking (PWSCC). In addition, the methods of surface finishing (buffing treatment) is being standardized, and thus the buffing treatment has been also recognized as the well-established method of improving stress. On the other hand, the long-term stability of peening techniques has been confirmed by accelerated test. However, the effectiveness of stress improvement by surface treatment is limited to thin layers and the effect of complicated residual stress distribution in the weld metal beneath the surface is not strictly taken into account for long-term stability. This paper, therefore, describes the accelerated tests, which confirmed that the long-term stability of the layer subjected to buffing treatment was equal to that subjected to WJP. The long-term reliability of very thin stress improved layer was also confirmed through a trial evaluation by thermal elastic-plastic creep analysis, even if the effect of complicated residual stress distribution in the weld metal was excessively taken into account. Considering the above findings, an approach is proposed for constructing the prediction method of the long-term reliability of stress improvement by surface finishing.


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