| 摘要 |
Provided is a method for continuously annealing a steel strip, which is capable of providing an annealing atmosphere having a low dew point suitable for annealing a steel strip containing an easily oxidizable element at low cost. A steel strip is annealed in a vertical annealing furnace including a heating zone and a soaking zone through which the steel strip is vertically conveyed, an atmosphere gas is supplied from 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 that is disposed outside of the furnace and includes 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 the reduced dew point, being returned into the furnace. A gas injector having a plurality of gas outlets arranged in a direction of a travel of the steel strip is disposed within a space spanning from the heating zone to the soaking zone to suppress a mixing of an atmosphere in the furnace upstream of the gas injector and an atmosphere in the furnace downstream of the gas injector, and a temperature of the steel strip passing through the gas injector is controlled to 600°C to 700°C. |
