| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for water-cooling a heated steel material without needing post-treatment for removing oxide film after water-cooling, and a steel material obtained by this water-cooling method. SOLUTION: The water cooling method for the steel material is performed as the followings, that is, in a formula of d<SB>H2O</SB>+d<SB>O2</SB>=7.98×10<SP>-4</SP>(T<SB>i</SB>-T<SB>o</SB>)dD<SB>O</SB>+ä5.50×10<SP>-3</SP>(T<SB>i</SB><SP>2</SP>-T<SB>o</SB><SP>2</SP>)-6.51(T<SB>i</SB>-T<SB>o</SB>)}/C<SB>R</SB>, respective conditions of a temperature at the start of the cooling with the water (T<SB>i</SB>), a temperature at the end of the cooling with the water (T<SB>o</SB>), a thickness of the steel material (d), a concentration of the oxygen dissolved in the cooling water (D<SB>O</SB>) and a cooling rate (C<SB>R</SB>), are set and the thickness of the oxide film (d<SB>H2O</SB>+d<SB>O2</SB>) is obtained so that the thickness of the oxide film on the surface of the steel material becomes≤15nm, without needing the post-treatment after water-cooling. COPYRIGHT: (C)2007,JPO&INPIT
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