| 摘要 |
PURPOSE:To permit the melt galvanizing of a small amount but a wide variety of products with a high efficiency by a procedure in which a steel plate subjected to a descaling treatment is treated with a water-soluble flux, dried, heated in a furnace with a nonoxidizing zone, a reduction zone, and cooling zone, and then plated with a molten metal without exposing it to the open air. CONSTITUTION:A steel plate subjected to a descaling treatment such as an acid washing, etc., is treated with a 3-20 deg. Be' water-soluble flux of a ZnCl2/NH4Cl molal ratio of 2.3-2.8, dried at 130-220 deg.C in the air, dried at 300-380 deg.C in the nonoxidation zone of a furnace filled with an ambient gas containing 1-8% CO, heat-treated at 440-750 deg.C ( or at 650-750 deg.C in case where plating bath is Al) in the reduction zone of a furnace filled with a gas consisting of 1-75% H2 and N2 and having a dew point of -20 deg.C, and then subjected, after being cooled to 440-550 deg.C in the cooling zone, to a melt galvanizing. Thus, the melt galvanizing of a small amount but a wide variety of objects can be attained with high efficiency. |
