| 摘要 |
PURPOSE:To provide galvannealed steel sheet excellent for the appearance, the workability and the deep drawability by specifying the temperature and the coating weight and re-heating the plated steel sheet under the prescribed conditions in executing the spray plaining of the molten Zn on the surface of the strip-shaped steel sheet. CONSTITUTION:After the surface of the low carbon Al-killed cold rolled steel sheet 1 is preliminarily cleaned, the steel sheet is heated at the temperature below the melting point of Zn by an induction heating equipment 5, and carried to a plating chamber 3 through a deflector roll 2. The temperature of the steel sheet 1 is measured by a thermometer 7, and the output of the heating equipment 5 is adjusted by an output control device 8 to correctly keep the temperature of the steel sheet 1 below the melting point of Zn. The molten Zn is blown from a nozzle 4 in the plating chamber 3 to execute the spray plating so that the coating weight per one side of the steel sheet 1 may be <=130g/m<2>. After the plated Zn is solidified, the plated steel sheet is placed in a re-heating furnace 6 where the temperature T of the steel sheet 1 is below the melting point of Zn, and the plated Zn is alloyed with Fe of the steel sheet by executing the re-heating under the conditions to satisfy the inequality with the heating time >=5sec. |
