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Title:
熱間圧延時の鋼材の加熱方法
Document Type and Number:
Japanese Patent JP4091834
Kind Code:
B2
Abstract:

To obtain a steel material excellent in the surface quality by preventing a red brittleness developed caused by concentration-melting of Cu mixed in the steel onto the surface in hot rolling, in the case of using scrap as an iron-source.

In a method for heating the steel material containing 0.05-3 mass% Cu precedent to the hot-rolling, the steel material is heated in an auxiliary atmosphere having ≤ 5 vol% steam under state of the lowest temperature of the steel material surface at ≥ 1,080°C. Further, in the method, the heating of the steel material is repeatedly performed with at least one time, to the performance of the heating with combustion gas and the heating in the oxidizing atmosphere having ≤ 5% vol% steam during not shorter time t (min) shown in the following relation with the lowest temperature T(K) on the steel material surface under state of the temperature at ≥ 1,080°C, at least one time, respectively. Log10(t) = -0.00301 × (T - 273) + 4.01.

COPYRIGHT: (C)2004,JPO


Inventors:
Yasumitsu Kondo
Kawasaki Kaoru
Application Number:
JP2002367678A
Publication Date:
May 28, 2008
Filing Date:
December 19, 2002
Export Citation:
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Assignee:
Nippon Steel Corporation
International Classes:
B21B45/00; C21D9/00; C21D1/76; C22C38/00; C22C38/16; C22C38/42
Domestic Patent References:
JP2002249824A
JP56116826A
Attorney, Agent or Firm:
Tomoyuki Yabuki
Tsugeko Shigeo