| 摘要 |
PROBLEM TO BE SOLVED: To provide a method of manufacturing an alloyed hot-dip galvanized steel sheet such that even when a steel belt containing 0.2 mass% or more of Si is subjected to alloying hot-dip galvanization, high plating adhesion and excellent plating appearance can be obtained, and tensile strength can be suppressed from decreasing by lowering alloying temperature.SOLUTION: A method of manufacturing an alloyed hot-dip galvanized steel sheet according to the present invention includes the processes of: annealing a steel belt by conveying the steel belt in an annealing furnace in the order of a heating zone including a direct fire type heating furnace, a soaking zone, and a cooling zone; subjecting the steel belt discharged from the cooling zone to Hot-dip galvanization; and heating and alloying the zinc plating. A mixed gas of a humidifying gas and a drying gas and a drying gas are supplied to the soaking zone, and a drying gas is supplied to the cooling zone, predetermined relation being satisfied among capacity Vr of the soaking zone, a gas flow rate Qrw and a water content Wr of the humidifying gas supplied to the soaking zone, a gas flow rate Qrd of the drying gas supplied to the soaking zone, a gas flow rate Qcd of the drying gas supplied to the cooling zone, and an average temperature Tr in the soaking zone.SELECTED DRAWING: Figure 1 |
