検索対象:     
報告書番号:
※ 半角英数字
 年 ~ 
 年

中性子回折法による大口径配管溶接部の残留応力測定; 残留応力分布に及ぼすSCCき裂進展及び補修溶接の影響

Residual stress measurement of large scaled welded pipe using neutron diffraction method; Effect of SCC crack propagation and repair weld on residual stress distribution

鈴木 裕士; 勝山 仁哉; 飛田 徹; 森井 幸生*

Suzuki, Hiroshi; Katsuyama, Jinya; Tobita, Toru; Morii, Yukio*

本研究では、中性子回折法による大型重量物の残留応力測定の実現を目的として、日本原子力研究開発機構の研究用原子炉JRR-3に整備された中性子応力測定装置RESA-1を高度化するとともに、500A-sch.80配管突合せ溶接試験体について、応力腐食割れ(SCC)を想定した模擬き裂導入前後、及び補修溶接施工後の溶接部近傍板厚内の残留応力分布の測定を試みた。その結果、As-weld状態における配管溶接部の残留応力分布は、これまでに有限要素法などにより評価された典型的な残留応力分布と同じ傾向を示した。配管内表面側の熱影響部に深さ10mmの模擬き裂を導入した場合には、模擬き裂導入部分の軸方向応力が緩和するが、曲げ応力成分や自己平衡応力成分の変化が小さいために、リガメント部の軸方向応力分布はほとんど変化しないことを確認した。一方、突合せ溶接配管溶接部の外周部に補修溶接を施工した場合には、配管軸方向の膜応力成分が増加するが、これは補修溶接に伴う曲げモーメントの変化が主要因である可能性を示した。以上のように、500A-sch.80配管突合せ溶接試験体の残留応力分布測定を通じて、中性子回折法が大型構造物の残留応力測定に対して有効な測定手段であることが実証された。

The RESA-1 neutron engineering diffractometer in the JRR-3 (Japan Research Reactor No.3) at the Japan Atomic Energy Agency, which is used for stress measurements, was upgraded to realize residual stress measurements of large scaled mechanical components. A series of residual stress measurements was made to obtain through-thickness residual stress distributions in a Type 304 stainless steel butt-welded pipe of 500A-sch.80 using the upgraded RESA-1 diffractometer. We evaluated effects of crack propagation such as stress corrosion cracking (SCC) and a part-circumference repair weld on the residual stress distributions induced by girth welding. Measured residual stress distributions near original girth weld revealed good agreement with typical results shown in some previous works using finite element method, deep hole drilling as well as neutron diffraction. After introducing a mock crack with 10 mm depth in heat affected zone on the inside wall of the pipe by electro discharge method, the axial residual stresses were found to be released in the part of the mock crack. However, changes in the through-wall bending stress component and the self-equilibrated stress component were negligible and hence the axial residual stress distribution in the ligament was remained in the original residual stresses near girth weld without the mock crack. Furthermore, changes in hoop and radial residual stress were also small. The residual stress distributions after a part repair welding on outer circumference of girth weld were significantly different from residual stress distributions near the original girth weld. Membrane residual stress was increased in the axial direction since the bending moment near the heat affected zone was changed due to repair weld. Throughout above studies, we evidenced that the neutron diffraction technique is useful and powerful tool for measuring residual stress distributions in large as well as thick mechanical components.

Access

:

- Accesses

InCites™

:

Altmetrics

:

[CLARIVATE ANALYTICS], [WEB OF SCIENCE], [HIGHLY CITED PAPER & CUP LOGO] and [HOT PAPER & FIRE LOGO] are trademarks of Clarivate Analytics, and/or its affiliated company or companies, and used herein by permission and/or license.