| 摘要 |
PROBLEM TO BE SOLVED: To provide a low yield point steel for a damper as an energy absorbing device in case of a big earthquake, and to provide its production method. SOLUTION: The low yield point steel for a damper has a composition comprising 0.001 to 0.050% C,≤0.80% Si, 0.1 to 2.0% Mn,≤0.020% P,≤0.015% S, Nb: 0.01 to 0.60% and also the quantity exceeding 8 times the C content,≤0.060% Al and≤0.006% N, and, if required, further comprising one or more kinds selected from Ti, V, B, Ni, Cu, Cr, Mo, Ca and REM by specified quantity, has a microstructure composed of a ferrite single phase, and does not have clear upper/lower yield points upon a tensile test. In its production method, a cast slab or a steel slab having the above components is heated at 1,000 to 1,300°C, is subjected to hot rolling in such a manner that it is finished at≥900°C and is subsequently let to cool, or is retained at 900 to 1,000°C for≥10 min after the hot rolling and is thereafter let to cool. COPYRIGHT: (C)2008,JPO&INPIT
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