PURPOSE: To obtain an adequate degree of alloying over the entire length of a coil in the production of the galvannealed steel sheet in a continuous galvannealing treatment stage.
CONSTITUTION: This method consists in adjusting the METSUKE (a unit to express amount of deposited metal) of the steel sheet by a gas throttling device 3 after galvannealing, then introducing the steel sheet into a high-frequency induction heating furnace 4 and subjecting the steel sheet to the alloying treatment. The Zn deposition on the steel sheet surface subjected to the adjustment of the METSUKE (unit) by the gas throttling device 3 is continuously measured with a hot Zn deposition meter 10 provided on the inlet side of the high-frequency induction heating furnace 4. The heating conditions of the steel sheet in the high-frequency induction heating furnace 4 is feed forward controlled in accordance with this measured value.
NAKAMURA AKIHIKO
IWABUCHI MASAHIRO
