| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a method for preventing an arch-state bending of a billet after cooling, caused by volume-expanding when the billet of a chromium-molybdenum steel having 0.28-0.48% carbon content after hot-rolling is air-cooled from about 900°C, by hindering the local generation of a bainite in about 500-600°C on the edge surface of the billet. Ž<P>SOLUTION: When the billet after hot-rolling, of the chromium-molybdenum steel having 0.28-0.48% carbon content is air-cooled from about 900°C, in order to cool at the slow speed which does not generate the bainitic structure on the edge surfaces 2, 2 of the billet in the cooling speed of the billet, the plurality of billets after hot-rolling are disposed at the interval composed of a gap 4 mutually obtaining the heat, and the heat-capacity of the billet is made to be large and the billet is air-cooled and the whole body of the billet is made to be ferrite-pearlitic structure to obtain the method for preventing the arch-state bending in the ordinary part 1 of the billet after cooling. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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