| 摘要 |
PURPOSE:To manufacture an alloy-hardened hot galvanized steel plate without causing melting damage to hot galvanizing pot, etc., by heating molten zinc prior to discharge when applying hot galvanization to the surface of a steel plate by discharging the molten zinc from a molten zinc exhaust device. CONSTITUTION:A steel plate 3 coming out of a pretreatment furnace 4 is introduced through a sealing device 5 into a hot galvanizer 1 confined with a nonoxidative gas, where it is then hot galvanized with molten zinc discharged from the molten zinc exhaust device 7. In this case, the molten zinc is heated to 440-800 deg.C by a heater 9 on its way toward the exhaust device 7 through a pump 8 from a molten zinc tank 2, blown against one side of the steel plate 3, and then blown off its excessive molten zinc adhered by means of a gas wipe nozzle 12. Then, the hot galvanized steel plate is subjected to an alloying treatment in an alloying furnace 11 where alloying occurs between the plated zinc and the steel plate to further raise the corrosion resistance of the hot galvanized surface. Since the molten zinc is raised in its temperature immediately before spraying, no damage to galvanizing pot occurs because the temperature inside the galvanizing pot is low. |
