| 摘要 |
PROBLEM TO BE SOLVED: To restrain the scale quantity generating and peeling during finish rolling to the minimum and to obtain the hot rolled steel plate having an excellent surface property without any flaws by controlling the fluctuation of the average temperature in cross section during the finish rolling of the steel plate so as to fall within the range of a specified temperature in the vicinity of Ar3 transformation point to execute up to the last rolling. SOLUTION: The steel 1 heated at the prescribed temperature with a heating furnace 2, the primary scale of which is removed with a high pressure descaling device 3 before rough rolling, is rolled with a roughing mill 4, thereafter it is rolled with a finishing mill 6 while compensating the temperature with an electrically heating power source 7 via a high pressure descaling device 5 before finishing rolling. The average temperature in cross section at the time of the finish rolling of the steel plate is controlled so as to fall in the narrow temperature range (30 deg.C or below) in the vicinity of Ar3 transformation point (Ar3±30 deg.C) to execute up to the last rolling. By this way, the surface temperature during rolling falls more than the conventional level to reduce the secondary scale generating quantity and thin the scale layer, the fluctuation of the temperature of the secondary scale is simultaneously reduced to restrain the scale peeling, thereby the yield of products is improved.
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