Study on stress measurement of large scaled welded tube
大型溶接配管の応力測定に関する研究
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、残留応力分布に及ぼすき裂進展や補修溶接の影響を定量的に評価することを目的とし、中性子回折法により直径,長さ,肉厚のSUS304鋼突合せ溶接配管の残留応力測定を行った。溶接後の残留応力分布は、これまでに報告されてきた有限要素解析結果に近い典型的な分布傾向を示した。配管内表面側に長さ30mm,深さ10mm,幅0.5mmの模擬き裂を導入すると、き裂導入部分において残留応力が緩和することを確認した。また、配管溶接部の外周部に補修溶接を施工すると、板厚全体にわたって引張応力が導入されるなど、補修溶接前の応力分布に比べて大きく変化することを確認した。このように、中性子応力測定技術は、実機相当の大型構造物の残留応力分布の測定に有効な手段であることを確認した。
Residual stress distributions near weld line of an austenitic large scaled butt-welded tube (500 mm diameter, 760 mm length and 28 mm wall thickness) were measured using the neutron diffraction technique. Typical residual stress distributions, which agreed well with some previous works using FEM, were measured in as-welded tube. After machining the slit with the size of 30 mm length, 10 mm depth and 0.5 mm width on the inside wall of the tube, the residual stresses in the axial direction were released in the part of the slit. On the other hand, the residual stress distributions after the repair welding on the outside wall were significantly changed like that tensile residual stresses were observed after the repair welding and compressive stresses were disappeared at all positions in all three directions. In this study, we indicated that the neutron diffraction technique is useful and powerful tool for measuring residual stress distribution in the large scaled mechanical components.