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川崎製鉄技報
KAWASAKI STEEL GIHO
Vol. 32(2000) No.2
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高強度・高靱性 590 MPa 鋼(SA440)を使用した建築鉄骨の加工条件の究明
Study of the Fabrication Method of 590 MPa Steel (SA440) with High Tensile Strength and High Ductility

泉  祐司(Yuji Izumi) 藤野  博(Hiroshi Fujino) 中島 松重(Matsushige Nakajima)
要旨 :
新しい高強度・高靱性の 590 MPa 鋼(SA440 鋼)は焼入―二相域焼入―焼戻しという特殊な熱処理を行う調質鋼であり,一般の鋼材に比べて溶接施工が著しく難しい材料である。本材料を使用した建築鉄骨の場合,塑性加工や大入熱溶接により母材の優れた性能が低下する恐れがあり,これを避けるための施工方法が課題となっていた。今回,ベンディングにより製造される板巻管と 4 面成形ボックスにおいて,諸々の材料試験・施工試験を行い,本来の材料が持つ高性能を加工後の鉄骨においても実現させるための加工条件の究明を行った。その結果塑性加工を受ける板巻き鋼管の造管後の機械的性能を熱処理を行うことにより母材同等レベルにできることを確認した。また,ボックスの施工試験を通じて健全な溶接継手を確保できることを確認した。
Synopsis :
"Harumi 1-choume development" is a big project which includes three high rise buildings (hight over 150 m) and ten middle/low rise buildings in Tokyo. The structural steel frame of these high rise buildings was designed involving box sections and pipes using a new steel material SA440 which has 590 MPa tensile strength. The box section has been manufactured by welding with much higher heat input after assembling steel plates, and the pipe section has been manufactured by bending a steel plate. SA440 is a particular material manufactured by undergoing heat treatment, including double quenching and tempering. The upper and lower limits of the yield strength (YP) and tensile strength (TS), and also yield ratio (YP/TS) are strictly regulated for this material. However, after the fabrication of this steel with much heat input or plastic deformation, there was a fear that the property of the material might have varied and YP, TS and YR might have exceeded the specified extent. In order to meet the requirement after the fabrication, we studied the heat treatment process of the pipe products, manufactured by bending, and the manufacturing process for the box products through production tests. From the result of these experiments, we studied the conditions of heat treatment and welding process which comply with the requirements. Consequently, Kawasaki Steel confirmed that it can ensure good mechanical property of pipes to which heat treatment in applied after receiving plastic deformation, and also obtain a good weld metal of the fabricated box section.
本文(PDF: 5P/253kb)




(c)JFE Steel Corporation, 2003