| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a hot-dip galvanizing method which does not cause an unplated defect on a base sheet to be plated such as a hot-rolled steel plate and a cold-rolled steel sheet, even though they contain various components, and has an advantageous manufacturing cost by using a method of pre-plating Ni. <P>SOLUTION: The hot-dip galvanizing method using a pickled hot-rolled steel plate or an annealed cold-rolled steel sheet as the base sheet to be plated comprises the steps of: when cleaning the surface of the base sheet, pre-plating it with Ni, rapidly heating it to a sheet temperature of 430 to 500°C at a heating rate of 20°C/sec or higher in a non-oxidative or reducing atmosphere, and hot-dipping it in a galvanizing bath, (a) controlling an amount of pre-plated Ni to 0.5 g/m<SP>2</SP>or more, for the pickled hot-rolled steel plate containing 0.2% or more Si; (b) controlling an amount of pre-plated Ni to 0.2 g/m<SP>2</SP>or more, for the pickled hot-rolled steel plate containing 0.2% or less Si; (c) controlling an amount of pre-plated Ni to 0.3 g/m<SP>2</SP>or more, for the annealed cold-rolled steel sheet containing 0.2% or more Si; and (d) controlling an amount of pre-plated Ni to 0.05 g/m<SP>2</SP>or more, for the annealed cold-rolled steel sheet containing 0.2% or less Si. <P>COPYRIGHT: (C)2007,JPO&INPIT |
