PURPOSE: To stably produce an H SECTION STEEL minimal in residual stress and having superior shape by minimizing the temp. difference between a flange part and a web part by applying water cooling to the flange part in the course of cooling at the time of producing an H section steel by means of hot rolling.
CONSTITUTION: At the time of producing an H section steel by subjecting a heated steel bloom to roughing by means of a universal roughing mill 3 and then to finish rolling by means of a universal finishing mill 4, water cooling zones 5, 6, 7 are provided to the outlet side of the universal roughing mill and the inlet and the outlet side of the universal finishing mill, respectively, to cool the flange part of a material to be rolled. At this time, on the basis of the cooling temp. transition curve of the web part from the temp. of the web part at the time of the initiation of water cooling of the flange part until the desired set temp. of the web part at the time of the completion of water cooling of the flange part is reached, the flow rate of cooling water is controlled so that the temp. of the flange part at the time of the completion of water cooling reaches the desired set temp. by performing the cooling of the flange part tracking the above curve, by which the temp. difference between the web part and the flange part can be minimized. By this method, the H section steel the wide flange shape excellent in shape and free from deterioration in toughness can be produced.
BABA KAZUFUMI
FUJIMOTO YOJI
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