| 摘要 |
Provided is a production method for an alloyed hot-dip-galvanized steel sheet, the production method being capable of achieving a favorable plated appearance and of suppressing reductions in tensile strength. This production method for an alloyed hot-dip-galvanized steel sheet has: a step wherein a steel strip is transported through the inside of an annealing furnace, in order through a heating zone that includes a direct-firing-type heating furnace, a soaking zone, and a cooling zone, and the steel strip is annealed; a step wherein, after being discharged from the cooling zone, the steel strip is hot-dip galvanized; and a step wherein the zinc-plating applied to the steel strip is heated and alloyed. The production method is characterized in that the soaking zone is supplied with a dry gas and with a mixed gas that includes a humidified gas and a dry gas, in that the cooling zone is supplied with a dry gas, and in that the volume (Vr) of the soaking zone, the gas flow rate (Qrw) and the water content (Wr) of the humidified gas supplied to the soaking zone, the gas flow rate (Qrd) of the dry gas supplied to the soaking zone, the gas flow rate (Qcd) of the dry gas supplied to the cooling zone, and the average temperature (Tr) inside the soaking zone satisfy a predetermined relationship. |
