METHOD FOR CONTINUOUSLY ANNEALING STEEL STRIP, APPARATUS FOR CONTINUOUSLY ANNEALING STEEL STRIP, METHOD FOR MANUFACTURING HOT-DIP GALVANIZED STEEL STRIP, AND APPARATUS FOR MANUFACTURING HOT-DIP GALVANIZED STEEL STRIP

摘要

A method for continuously annealing a steel strip includes annealing the steel strip in a vertical annealing furnace, an atmosphere in the furnace being separated by a partition disposed within a space spanning from the heating zone to the soaking zone. An atmosphere gas is supplied from an outside of the furnace into the furnace to form a furnace gas that is discharged from a steel strip entrance at a lower portion of the heating zone, a part of the furnace gas is sucked and discharged into a refiner including a deoxygenator and a dehumidifier such that oxygen and moisture in the part of the furnace gas are removed to form a gas having a lowered dew point, and the gas having a lowered dew point is returned into the furnace. The method further includes controlling a temperature of the steel strip passing through the partition to a range of 550° C. to 700° C.

主权项

1. A method for continuously annealing a steel strip, the method comprising:
annealing the steel strip in a vertical annealing furnace including a heating zone and a soaking zone arranged in this order from an entry side of the furnace through which the steel strip is vertically conveyed, an atmosphere in the furnace being separated by a partition disposed within the heating zone, wherein:
an atmosphere gas is supplied from an outside of the furnace into the furnace to form a furnace gas that is discharged from a steel strip entrance at the entry side of the furnace;a part of the furnace gas is sucked and discharged into a refiner, which is disposed outside of the furnace, including a deoxygenator and a dehumidifier such that oxygen and moisture in the part of the furnace gas are removed to form a refiner gas having a lowered dew point; andthe refiner gas having the lowered dew point is returned into the furnace; and controlling a temperature of the steel strip passing through the partition to a range of 550° C. to 700° C.