| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a hot-dip galvanized steel sheet which has enhanced appearance properties (specifically free from unplated portions and alloying ununiformity) and has a plated layer having enhanced adhesiveness to a base steel sheet over a width direction, and to provide a method for manufacturing the hot-dip galvannealed steel sheet. <P>SOLUTION: This manufacturing method includes: the first step of heating the steel sheet under an atmosphere in a pre-heating furnace in which the oxygen amount is controlled to 0.00010-0.05 vol.% and the water-vapor amount is controlled to 10-30 vol.%, while controlling an annealing-starting temperature to 550-700°C; and the second step of heating the steel sheet under an atmosphere in an annealing furnace in which the oxygen amount is controlled to 0.0001 vol.% or more but less than 0.10 vol.% and the water-vapor amount is controlled to 10-30 vol.%, while adequately controlling the Si amount (mass%) contained in the base steel sheet, the annealing period of time t (second) and the annealing termination temperature T (°C). <P>COPYRIGHT: (C)2011,JPO&INPIT</p> |
