| 摘要 |
PROBLEM TO BE SOLVED: To provide low-cost steel for a vibration absorbing damper which has a low yield point and high toughness, and to provide its production method. SOLUTION: The steel for a vibration absorbing damper has a composition comprising 0.02 to 0.07% C,≤0.4% Si, 0.1 to 0.5% Mn,≤0.050% P,≤0.020% S,≤0.05% Al,≤0.005% O and≤0.006% N, and the balance Fe with inevitable impurities. The steel has a metallic structure in which the occupancy ratio of ferrite is≥90 area%, the ferrite grain size number is 5.0 to 8.5, and the hardness in the ferrite grains is≥95 by HV<SB>0.1</SB>. The steel for a vibration absorbing damper has a yield point of 205 to 245 N/mm<SP>2</SP>, and an absorbed energy vE<SB>0</SB>of≥200 J. In its production method, the steel is hot-rolled, is thereafter reheated at 890 to 950°C, is immediately subjected to rapid cooling to≤200°C at a cooling ratio of≥10°C/s, and is subsequently reheated at 500 to 700°C at a temperature rising rate of 0.2 to 5°C/s, and, after the arrival at the objective heating temperature, the steel is held to the temperature for≥5 min. COPYRIGHT: (C)2005,JPO&NCIPI
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